flutter_flutter/sky/engine/wtf/PartitionAllocTest.cpp

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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#include "flutter/sky/engine/wtf/PartitionAlloc.h"

#include <gtest/gtest.h>
#include <stdlib.h>
#include <string.h>
#include "flutter/sky/engine/wtf/BitwiseOperations.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"
#include "flutter/sky/engine/wtf/PassOwnPtr.h"

#if OS(POSIX)
#include <sys/mman.h>

#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif  // OS(POSIX)

#if !defined(MEMORY_TOOL_REPLACES_ALLOCATOR)

namespace {

static const size_t kTestMaxAllocation = 4096;
static SizeSpecificPartitionAllocator<kTestMaxAllocation> allocator;
static PartitionAllocatorGeneric genericAllocator;

static const size_t kTestAllocSize = 16;
#if !ENABLE(ASSERT)
static const size_t kPointerOffset = 0;
static const size_t kExtraAllocSize = 0;
#else
static const size_t kPointerOffset = WTF::kCookieSize;
static const size_t kExtraAllocSize = WTF::kCookieSize * 2;
#endif
static const size_t kRealAllocSize = kTestAllocSize + kExtraAllocSize;
static const size_t kTestBucketIndex = kRealAllocSize >> WTF::kBucketShift;

static void TestSetup() {
  allocator.init();
  genericAllocator.init();
}

static void TestShutdown() {
#ifndef NDEBUG
  // Test that the partition statistic dumping code works. Previously, it
  // bitrotted because no test calls it.
  partitionDumpStats(*allocator.root());
#endif

  // We expect no leaks in the general case. We have a test for leak
  // detection.
  EXPECT_TRUE(allocator.shutdown());
  EXPECT_TRUE(genericAllocator.shutdown());
}

static WTF::PartitionPage* GetFullPage(size_t size) {
  size_t realSize = size + kExtraAllocSize;
  size_t bucketIdx = realSize >> WTF::kBucketShift;
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[bucketIdx];
  size_t numSlots =
      (bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) / realSize;
  void* first = 0;
  void* last = 0;
  size_t i;
  for (i = 0; i < numSlots; ++i) {
    void* ptr = partitionAlloc(allocator.root(), size);
    EXPECT_TRUE(ptr);
    if (!i)
      first = WTF::partitionCookieFreePointerAdjust(ptr);
    else if (i == numSlots - 1)
      last = WTF::partitionCookieFreePointerAdjust(ptr);
  }
  EXPECT_EQ(WTF::partitionPointerToPage(first),
            WTF::partitionPointerToPage(last));
  if (bucket->numSystemPagesPerSlotSpan == WTF::kNumSystemPagesPerPartitionPage)
    EXPECT_EQ(reinterpret_cast<size_t>(first) & WTF::kPartitionPageBaseMask,
              reinterpret_cast<size_t>(last) & WTF::kPartitionPageBaseMask);
  EXPECT_EQ(numSlots,
            static_cast<size_t>(bucket->activePagesHead->numAllocatedSlots));
  EXPECT_EQ(0, bucket->activePagesHead->freelistHead);
  EXPECT_TRUE(bucket->activePagesHead);
  EXPECT_TRUE(bucket->activePagesHead != &WTF::PartitionRootGeneric::gSeedPage);
  return bucket->activePagesHead;
}

static void FreeFullPage(WTF::PartitionPage* page) {
  size_t size = page->bucket->slotSize;
  size_t numSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) / size;
  EXPECT_EQ(numSlots, static_cast<size_t>(abs(page->numAllocatedSlots)));
  char* ptr = reinterpret_cast<char*>(partitionPageToPointer(page));
  size_t i;
  for (i = 0; i < numSlots; ++i) {
    partitionFree(ptr + kPointerOffset);
    ptr += size;
  }
}

static void CycleFreeCache(size_t size) {
  size_t realSize = size + kExtraAllocSize;
  size_t bucketIdx = realSize >> WTF::kBucketShift;
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[bucketIdx];
  ASSERT(!bucket->activePagesHead->numAllocatedSlots);

  for (size_t i = 0; i < WTF::kMaxFreeableSpans; ++i) {
    void* ptr = partitionAlloc(allocator.root(), size);
    EXPECT_EQ(1, bucket->activePagesHead->numAllocatedSlots);
    partitionFree(ptr);
    EXPECT_EQ(0, bucket->activePagesHead->numAllocatedSlots);
    EXPECT_NE(-1, bucket->activePagesHead->freeCacheIndex);
  }
}

static void CycleGenericFreeCache(size_t size) {
  for (size_t i = 0; i < WTF::kMaxFreeableSpans; ++i) {
    void* ptr = partitionAllocGeneric(genericAllocator.root(), size);
    WTF::PartitionPage* page =
        WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
    WTF::PartitionBucket* bucket = page->bucket;
    EXPECT_EQ(1, bucket->activePagesHead->numAllocatedSlots);
    partitionFreeGeneric(genericAllocator.root(), ptr);
    EXPECT_EQ(0, bucket->activePagesHead->numAllocatedSlots);
    EXPECT_NE(-1, bucket->activePagesHead->freeCacheIndex);
  }
}

// Check that the most basic of allocate / free pairs work.
TEST(PartitionAllocTest, Basic) {
  TestSetup();
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[kTestBucketIndex];
  WTF::PartitionPage* seedPage = &WTF::PartitionRootGeneric::gSeedPage;

  EXPECT_FALSE(bucket->freePagesHead);
  EXPECT_EQ(seedPage, bucket->activePagesHead);
  EXPECT_EQ(0, bucket->activePagesHead->nextPage);

  void* ptr = partitionAlloc(allocator.root(), kTestAllocSize);
  EXPECT_TRUE(ptr);
  EXPECT_EQ(kPointerOffset,
            reinterpret_cast<size_t>(ptr) & WTF::kPartitionPageOffsetMask);
  // Check that the offset appears to include a guard page.
  EXPECT_EQ(WTF::kPartitionPageSize + kPointerOffset,
            reinterpret_cast<size_t>(ptr) & WTF::kSuperPageOffsetMask);

  partitionFree(ptr);
  // Expect that the last active page does not get tossed to the freelist.
  EXPECT_FALSE(bucket->freePagesHead);

  TestShutdown();
}

// Check that we can detect a memory leak.
TEST(PartitionAllocTest, SimpleLeak) {
  TestSetup();
  void* leakedPtr = partitionAlloc(allocator.root(), kTestAllocSize);
  (void)leakedPtr;
  void* leakedPtr2 =
      partitionAllocGeneric(genericAllocator.root(), kTestAllocSize);
  (void)leakedPtr2;
  EXPECT_FALSE(allocator.shutdown());
  EXPECT_FALSE(genericAllocator.shutdown());
}

// Test multiple allocations, and freelist handling.
TEST(PartitionAllocTest, MultiAlloc) {
  TestSetup();

  char* ptr1 =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  char* ptr2 =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_TRUE(ptr1);
  EXPECT_TRUE(ptr2);
  ptrdiff_t diff = ptr2 - ptr1;
  EXPECT_EQ(static_cast<ptrdiff_t>(kRealAllocSize), diff);

  // Check that we re-use the just-freed slot.
  partitionFree(ptr2);
  ptr2 =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_TRUE(ptr2);
  diff = ptr2 - ptr1;
  EXPECT_EQ(static_cast<ptrdiff_t>(kRealAllocSize), diff);
  partitionFree(ptr1);
  ptr1 =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_TRUE(ptr1);
  diff = ptr2 - ptr1;
  EXPECT_EQ(static_cast<ptrdiff_t>(kRealAllocSize), diff);

  char* ptr3 =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_TRUE(ptr3);
  diff = ptr3 - ptr1;
  EXPECT_EQ(static_cast<ptrdiff_t>(kRealAllocSize * 2), diff);

  partitionFree(ptr1);
  partitionFree(ptr2);
  partitionFree(ptr3);

  TestShutdown();
}

// Test a bucket with multiple pages.
TEST(PartitionAllocTest, MultiPages) {
  TestSetup();
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[kTestBucketIndex];

  WTF::PartitionPage* page = GetFullPage(kTestAllocSize);
  FreeFullPage(page);
  EXPECT_FALSE(bucket->freePagesHead);
  EXPECT_EQ(page, bucket->activePagesHead);
  EXPECT_EQ(0, page->nextPage);
  EXPECT_EQ(0, page->numAllocatedSlots);

  page = GetFullPage(kTestAllocSize);
  WTF::PartitionPage* page2 = GetFullPage(kTestAllocSize);

  EXPECT_EQ(page2, bucket->activePagesHead);
  EXPECT_EQ(0, page2->nextPage);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(partitionPageToPointer(page)) &
                WTF::kSuperPageBaseMask,
            reinterpret_cast<uintptr_t>(partitionPageToPointer(page2)) &
                WTF::kSuperPageBaseMask);

  // Fully free the non-current page. It should not be freelisted because
  // there is no other immediately useable page. The other page is full.
  FreeFullPage(page);
  EXPECT_EQ(0, page->numAllocatedSlots);
  EXPECT_FALSE(bucket->freePagesHead);
  EXPECT_EQ(page, bucket->activePagesHead);

  // Allocate a new page, it should pull from the freelist.
  page = GetFullPage(kTestAllocSize);
  EXPECT_FALSE(bucket->freePagesHead);
  EXPECT_EQ(page, bucket->activePagesHead);

  FreeFullPage(page);
  FreeFullPage(page2);
  EXPECT_EQ(0, page->numAllocatedSlots);
  EXPECT_EQ(0, page2->numAllocatedSlots);
  EXPECT_EQ(0, page2->numUnprovisionedSlots);
  EXPECT_NE(-1, page2->freeCacheIndex);

  TestShutdown();
}

// Test some finer aspects of internal page transitions.
TEST(PartitionAllocTest, PageTransitions) {
  TestSetup();
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[kTestBucketIndex];

  WTF::PartitionPage* page1 = GetFullPage(kTestAllocSize);
  EXPECT_EQ(page1, bucket->activePagesHead);
  EXPECT_EQ(0, page1->nextPage);
  WTF::PartitionPage* page2 = GetFullPage(kTestAllocSize);
  EXPECT_EQ(page2, bucket->activePagesHead);
  EXPECT_EQ(0, page2->nextPage);

  // Bounce page1 back into the non-full list then fill it up again.
  char* ptr =
      reinterpret_cast<char*>(partitionPageToPointer(page1)) + kPointerOffset;
  partitionFree(ptr);
  EXPECT_EQ(page1, bucket->activePagesHead);
  (void)partitionAlloc(allocator.root(), kTestAllocSize);
  EXPECT_EQ(page1, bucket->activePagesHead);
  EXPECT_EQ(page2, bucket->activePagesHead->nextPage);

  // Allocating another page at this point should cause us to scan over page1
  // (which is both full and NOT our current page), and evict it from the
  // freelist. Older code had a O(n^2) condition due to failure to do this.
  WTF::PartitionPage* page3 = GetFullPage(kTestAllocSize);
  EXPECT_EQ(page3, bucket->activePagesHead);
  EXPECT_EQ(0, page3->nextPage);

  // Work out a pointer into page2 and free it.
  ptr = reinterpret_cast<char*>(partitionPageToPointer(page2)) + kPointerOffset;
  partitionFree(ptr);
  // Trying to allocate at this time should cause us to cycle around to page2
  // and find the recently freed slot.
  char* newPtr =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_EQ(ptr, newPtr);
  EXPECT_EQ(page2, bucket->activePagesHead);
  EXPECT_EQ(page3, page2->nextPage);

  // Work out a pointer into page1 and free it. This should pull the page
  // back into the list of available pages.
  ptr = reinterpret_cast<char*>(partitionPageToPointer(page1)) + kPointerOffset;
  partitionFree(ptr);
  // This allocation should be satisfied by page1.
  newPtr =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  EXPECT_EQ(ptr, newPtr);
  EXPECT_EQ(page1, bucket->activePagesHead);
  EXPECT_EQ(page2, page1->nextPage);

  FreeFullPage(page3);
  FreeFullPage(page2);
  FreeFullPage(page1);

  // Allocating whilst in this state exposed a bug, so keep the test.
  ptr =
      reinterpret_cast<char*>(partitionAlloc(allocator.root(), kTestAllocSize));
  partitionFree(ptr);

  TestShutdown();
}

// Test some corner cases relating to page transitions in the internal
// free page list metadata bucket.
TEST(PartitionAllocTest, FreePageListPageTransitions) {
  TestSetup();
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[kTestBucketIndex];

  size_t numToFillFreeListPage =
      WTF::kPartitionPageSize / (sizeof(WTF::PartitionPage) + kExtraAllocSize);
  // The +1 is because we need to account for the fact that the current page
  // never gets thrown on the freelist.
  ++numToFillFreeListPage;
  OwnPtr<WTF::PartitionPage* []> pages =
      adoptArrayPtr(new WTF::PartitionPage*[numToFillFreeListPage]);

  size_t i;
  for (i = 0; i < numToFillFreeListPage; ++i) {
    pages[i] = GetFullPage(kTestAllocSize);
  }
  EXPECT_EQ(pages[numToFillFreeListPage - 1], bucket->activePagesHead);
  for (i = 0; i < numToFillFreeListPage; ++i)
    FreeFullPage(pages[i]);
  EXPECT_EQ(0, bucket->activePagesHead->numAllocatedSlots);
  EXPECT_NE(-1, bucket->activePagesHead->nextPage->freeCacheIndex);
  EXPECT_EQ(0, bucket->activePagesHead->nextPage->numAllocatedSlots);
  EXPECT_EQ(0, bucket->activePagesHead->nextPage->numUnprovisionedSlots);

  // Allocate / free in a different bucket size so we get control of a
  // different free page list. We need two pages because one will be the last
  // active page and not get freed.
  WTF::PartitionPage* page1 = GetFullPage(kTestAllocSize * 2);
  WTF::PartitionPage* page2 = GetFullPage(kTestAllocSize * 2);
  FreeFullPage(page1);
  FreeFullPage(page2);

  // If we re-allocate all kTestAllocSize allocations, we'll pull all the
  // free pages and end up freeing the first page for free page objects.
  // It's getting a bit tricky but a nice re-entrancy is going on:
  // alloc(kTestAllocSize) -> pulls page from free page list ->
  // free(PartitionFreepagelistEntry) -> last entry in page freed ->
  // alloc(PartitionFreepagelistEntry).
  for (i = 0; i < numToFillFreeListPage; ++i) {
    pages[i] = GetFullPage(kTestAllocSize);
  }
  EXPECT_EQ(pages[numToFillFreeListPage - 1], bucket->activePagesHead);

  // As part of the final free-up, we'll test another re-entrancy:
  // free(kTestAllocSize) -> last entry in page freed ->
  // alloc(PartitionFreepagelistEntry) -> pulls page from free page list ->
  // free(PartitionFreepagelistEntry)
  for (i = 0; i < numToFillFreeListPage; ++i)
    FreeFullPage(pages[i]);
  EXPECT_EQ(0, bucket->activePagesHead->numAllocatedSlots);
  EXPECT_NE(-1, bucket->activePagesHead->nextPage->freeCacheIndex);
  EXPECT_EQ(0, bucket->activePagesHead->nextPage->numAllocatedSlots);
  EXPECT_EQ(0, bucket->activePagesHead->nextPage->numUnprovisionedSlots);

  TestShutdown();
}

// Test a large series of allocations that cross more than one underlying
// 64KB super page allocation.
TEST(PartitionAllocTest, MultiPageAllocs) {
  TestSetup();
  // This is guaranteed to cross a super page boundary because the first
  // partition page "slot" will be taken up by a guard page.
  size_t numPagesNeeded = WTF::kNumPartitionPagesPerSuperPage;
  // The super page should begin and end in a guard so we one less page in
  // order to allocate a single page in the new super page.
  --numPagesNeeded;

  EXPECT_GT(numPagesNeeded, 1u);
  OwnPtr<WTF::PartitionPage* []> pages;
  pages = adoptArrayPtr(new WTF::PartitionPage*[numPagesNeeded]);
  uintptr_t firstSuperPageBase = 0;
  size_t i;
  for (i = 0; i < numPagesNeeded; ++i) {
    pages[i] = GetFullPage(kTestAllocSize);
    void* storagePtr = partitionPageToPointer(pages[i]);
    if (!i)
      firstSuperPageBase =
          reinterpret_cast<uintptr_t>(storagePtr) & WTF::kSuperPageBaseMask;
    if (i == numPagesNeeded - 1) {
      uintptr_t secondSuperPageBase =
          reinterpret_cast<uintptr_t>(storagePtr) & WTF::kSuperPageBaseMask;
      uintptr_t secondSuperPageOffset =
          reinterpret_cast<uintptr_t>(storagePtr) & WTF::kSuperPageOffsetMask;
      EXPECT_FALSE(secondSuperPageBase == firstSuperPageBase);
      // Check that we allocated a guard page for the second page.
      EXPECT_EQ(WTF::kPartitionPageSize, secondSuperPageOffset);
    }
  }
  for (i = 0; i < numPagesNeeded; ++i)
    FreeFullPage(pages[i]);

  TestShutdown();
}

// Test the generic allocation functions that can handle arbitrary sizes and
// reallocing etc.
TEST(PartitionAllocTest, GenericAlloc) {
  TestSetup();

  void* ptr = partitionAllocGeneric(genericAllocator.root(), 1);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);
  ptr = partitionAllocGeneric(genericAllocator.root(),
                              WTF::kGenericMaxBucketed + 1);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  ptr = partitionAllocGeneric(genericAllocator.root(), 1);
  EXPECT_TRUE(ptr);
  void* origPtr = ptr;
  char* charPtr = static_cast<char*>(ptr);
  *charPtr = 'A';

  // Change the size of the realloc, remaining inside the same bucket.
  void* newPtr = partitionReallocGeneric(genericAllocator.root(), ptr, 2);
  EXPECT_EQ(ptr, newPtr);
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr, 1);
  EXPECT_EQ(ptr, newPtr);
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr,
                                   WTF::kGenericSmallestBucket);
  EXPECT_EQ(ptr, newPtr);

  // Change the size of the realloc, switching buckets.
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr,
                                   WTF::kGenericSmallestBucket + 1);
  EXPECT_NE(newPtr, ptr);
  // Check that the realloc copied correctly.
  char* newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'A');
#if ENABLE(ASSERT)
  // Subtle: this checks for an old bug where we copied too much from the
  // source of the realloc. The condition can be detected by a trashing of
  // the uninitialized value in the space of the upsized allocation.
  EXPECT_EQ(
      WTF::kUninitializedByte,
      static_cast<unsigned char>(*(newCharPtr + WTF::kGenericSmallestBucket)));
#endif
  *newCharPtr = 'B';
  // The realloc moved. To check that the old allocation was freed, we can
  // do an alloc of the old allocation size and check that the old allocation
  // address is at the head of the freelist and reused.
  void* reusedPtr = partitionAllocGeneric(genericAllocator.root(), 1);
  EXPECT_EQ(reusedPtr, origPtr);
  partitionFreeGeneric(genericAllocator.root(), reusedPtr);

  // Downsize the realloc.
  ptr = newPtr;
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr, 1);
  EXPECT_EQ(newPtr, origPtr);
  newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'B');
  *newCharPtr = 'C';

  // Upsize the realloc to outside the partition.
  ptr = newPtr;
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr,
                                   WTF::kGenericMaxBucketed + 1);
  EXPECT_NE(newPtr, ptr);
  newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'C');
  *newCharPtr = 'D';

  // Upsize and downsize the realloc, remaining outside the partition.
  ptr = newPtr;
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr,
                                   WTF::kGenericMaxBucketed * 10);
  newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'D');
  *newCharPtr = 'E';
  ptr = newPtr;
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr,
                                   WTF::kGenericMaxBucketed * 2);
  newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'E');
  *newCharPtr = 'F';

  // Downsize the realloc to inside the partition.
  ptr = newPtr;
  newPtr = partitionReallocGeneric(genericAllocator.root(), ptr, 1);
  EXPECT_NE(newPtr, ptr);
  EXPECT_EQ(newPtr, origPtr);
  newCharPtr = static_cast<char*>(newPtr);
  EXPECT_EQ(*newCharPtr, 'F');

  partitionFreeGeneric(genericAllocator.root(), newPtr);
  TestShutdown();
}

// Test the generic allocation functions can handle some specific sizes of
// interest.
TEST(PartitionAllocTest, GenericAllocSizes) {
  TestSetup();

  void* ptr = partitionAllocGeneric(genericAllocator.root(), 0);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // kPartitionPageSize is interesting because it results in just one
  // allocation per page, which tripped up some corner cases.
  size_t size = WTF::kPartitionPageSize - kExtraAllocSize;
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  void* ptr2 = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr2);
  partitionFreeGeneric(genericAllocator.root(), ptr);
  // Should be freeable at this point.
  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_NE(-1, page->freeCacheIndex);
  partitionFreeGeneric(genericAllocator.root(), ptr2);

  size = (((WTF::kPartitionPageSize * WTF::kMaxPartitionPagesPerSlotSpan) -
           WTF::kSystemPageSize) /
          2) -
         kExtraAllocSize;
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  memset(ptr, 'A', size);
  ptr2 = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr2);
  void* ptr3 = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr3);
  void* ptr4 = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr4);

  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  WTF::PartitionPage* page2 =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr3));
  EXPECT_NE(page, page2);

  partitionFreeGeneric(genericAllocator.root(), ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr3);
  partitionFreeGeneric(genericAllocator.root(), ptr2);
  // Should be freeable at this point.
  EXPECT_NE(-1, page->freeCacheIndex);
  EXPECT_EQ(0, page->numAllocatedSlots);
  EXPECT_EQ(0, page->numUnprovisionedSlots);
  void* newPtr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_EQ(ptr3, newPtr);
  newPtr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_EQ(ptr2, newPtr);
#if OS(LINUX) && !ENABLE(ASSERT)
  // On Linux, we have a guarantee that freelisting a page should cause its
  // contents to be nulled out. We check for null here to detect an bug we
  // had where a large slot size was causing us to not properly free all
  // resources back to the system.
  // We only run the check when asserts are disabled because when they are
  // enabled, the allocated area is overwritten with an "uninitialized"
  // byte pattern.
  EXPECT_EQ(0, *(reinterpret_cast<char*>(newPtr) + (size - 1)));
#endif
  partitionFreeGeneric(genericAllocator.root(), newPtr);
  partitionFreeGeneric(genericAllocator.root(), ptr3);
  partitionFreeGeneric(genericAllocator.root(), ptr4);

  // Can we allocate a massive (512MB) size?
  ptr = partitionAllocGeneric(genericAllocator.root(), 512 * 1024 * 1024);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Check a more reasonable, but still direct mapped, size.
  // Chop a system page and a byte off to test for rounding errors.
  size = 20 * 1024 * 1024;
  size -= WTF::kSystemPageSize;
  size -= 1;
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  char* charPtr = reinterpret_cast<char*>(ptr);
  *(charPtr + (size - 1)) = 'A';
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Can we free null?
  partitionFreeGeneric(genericAllocator.root(), 0);

  // Do we correctly get a null for a failed allocation?
  EXPECT_EQ(0, partitionAllocGenericFlags(genericAllocator.root(),
                                          WTF::PartitionAllocReturnNull,
                                          3u * 1024 * 1024 * 1024));

  TestShutdown();
}

// Test that we can fetch the real allocated size after an allocation.
TEST(PartitionAllocTest, GenericAllocGetSize) {
  TestSetup();

  void* ptr;
  size_t requestedSize, actualSize, predictedSize;

  EXPECT_TRUE(partitionAllocSupportsGetSize());

  // Allocate something small.
  requestedSize = 511 - kExtraAllocSize;
  predictedSize =
      partitionAllocActualSize(genericAllocator.root(), requestedSize);
  ptr = partitionAllocGeneric(genericAllocator.root(), requestedSize);
  EXPECT_TRUE(ptr);
  actualSize = partitionAllocGetSize(ptr);
  EXPECT_EQ(predictedSize, actualSize);
  EXPECT_LT(requestedSize, actualSize);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Allocate a size that should be a perfect match for a bucket, because it
  // is an exact power of 2.
  requestedSize = (256 * 1024) - kExtraAllocSize;
  predictedSize =
      partitionAllocActualSize(genericAllocator.root(), requestedSize);
  ptr = partitionAllocGeneric(genericAllocator.root(), requestedSize);
  EXPECT_TRUE(ptr);
  actualSize = partitionAllocGetSize(ptr);
  EXPECT_EQ(predictedSize, actualSize);
  EXPECT_EQ(requestedSize, actualSize);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Allocate a size that is a system page smaller than a bucket. GetSize()
  // should return a larger size than we asked for now.
  requestedSize = (256 * 1024) - WTF::kSystemPageSize - kExtraAllocSize;
  predictedSize =
      partitionAllocActualSize(genericAllocator.root(), requestedSize);
  ptr = partitionAllocGeneric(genericAllocator.root(), requestedSize);
  EXPECT_TRUE(ptr);
  actualSize = partitionAllocGetSize(ptr);
  EXPECT_EQ(predictedSize, actualSize);
  EXPECT_EQ(requestedSize + WTF::kSystemPageSize, actualSize);
  // Check that we can write at the end of the reported size too.
  char* charPtr = reinterpret_cast<char*>(ptr);
  *(charPtr + (actualSize - 1)) = 'A';
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Allocate something very large, and uneven.
  requestedSize = 512 * 1024 * 1024 - 1;
  predictedSize =
      partitionAllocActualSize(genericAllocator.root(), requestedSize);
  ptr = partitionAllocGeneric(genericAllocator.root(), requestedSize);
  EXPECT_TRUE(ptr);
  actualSize = partitionAllocGetSize(ptr);
  EXPECT_EQ(predictedSize, actualSize);
  EXPECT_LT(requestedSize, actualSize);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Too large allocation.
  requestedSize = INT_MAX;
  predictedSize =
      partitionAllocActualSize(genericAllocator.root(), requestedSize);
  EXPECT_EQ(requestedSize, predictedSize);

  TestShutdown();
}

// Test the realloc() contract.
TEST(PartitionAllocTest, Realloc) {
  TestSetup();

  // realloc(0, size) should be equivalent to malloc().
  void* ptr =
      partitionReallocGeneric(genericAllocator.root(), 0, kTestAllocSize);
  memset(ptr, 'A', kTestAllocSize);
  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  // realloc(ptr, 0) should be equivalent to free().
  void* ptr2 = partitionReallocGeneric(genericAllocator.root(), ptr, 0);
  EXPECT_EQ(0, ptr2);
  EXPECT_EQ(WTF::partitionCookieFreePointerAdjust(ptr), page->freelistHead);

  // Test that growing an allocation with realloc() copies everything from the
  // old allocation.
  size_t size = WTF::kSystemPageSize - kExtraAllocSize;
  EXPECT_EQ(size, partitionAllocActualSize(genericAllocator.root(), size));
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  memset(ptr, 'A', size);
  ptr2 = partitionReallocGeneric(genericAllocator.root(), ptr, size + 1);
  EXPECT_NE(ptr, ptr2);
  char* charPtr2 = static_cast<char*>(ptr2);
  EXPECT_EQ('A', charPtr2[0]);
  EXPECT_EQ('A', charPtr2[size - 1]);
#if ENABLE(ASSERT)
  EXPECT_EQ(WTF::kUninitializedByte,
            static_cast<unsigned char>(charPtr2[size]));
#endif

  // Test that shrinking an allocation with realloc() also copies everything
  // from the old allocation.
  ptr = partitionReallocGeneric(genericAllocator.root(), ptr2, size - 1);
  EXPECT_NE(ptr2, ptr);
  char* charPtr = static_cast<char*>(ptr);
  EXPECT_EQ('A', charPtr[0]);
  EXPECT_EQ('A', charPtr[size - 2]);
#if ENABLE(ASSERT)
  EXPECT_EQ(WTF::kUninitializedByte,
            static_cast<unsigned char>(charPtr[size - 1]));
#endif

  partitionFreeGeneric(genericAllocator.root(), ptr);

  // Test that shrinking a direct mapped allocation happens in-place.
  size = WTF::kGenericMaxBucketed + 16 * WTF::kSystemPageSize;
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  size_t actualSize = partitionAllocGetSize(ptr);
  ptr2 = partitionReallocGeneric(
      genericAllocator.root(), ptr,
      WTF::kGenericMaxBucketed + 8 * WTF::kSystemPageSize);
  EXPECT_EQ(ptr, ptr2);
  EXPECT_EQ(actualSize - 8 * WTF::kSystemPageSize, partitionAllocGetSize(ptr2));

  // Test that a previously in-place shrunk direct mapped allocation can be
  // expanded up again within its original size.
  ptr = partitionReallocGeneric(genericAllocator.root(), ptr2,
                                size - WTF::kSystemPageSize);
  EXPECT_EQ(ptr2, ptr);
  EXPECT_EQ(actualSize - WTF::kSystemPageSize, partitionAllocGetSize(ptr));

  // Test that a direct mapped allocation is performed not in-place when the
  // new size is small enough.
  ptr2 = partitionReallocGeneric(genericAllocator.root(), ptr,
                                 WTF::kSystemPageSize);
  EXPECT_NE(ptr, ptr2);

  partitionFreeGeneric(genericAllocator.root(), ptr2);

  TestShutdown();
}

// Tests the handing out of freelists for partial pages.
TEST(PartitionAllocTest, PartialPageFreelists) {
  TestSetup();

  size_t bigSize = allocator.root()->maxAllocation - kExtraAllocSize;
  EXPECT_EQ(WTF::kSystemPageSize - WTF::kAllocationGranularity,
            bigSize + kExtraAllocSize);
  size_t bucketIdx = (bigSize + kExtraAllocSize) >> WTF::kBucketShift;
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[bucketIdx];
  EXPECT_EQ(0, bucket->freePagesHead);

  void* ptr = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr);

  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  size_t totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (bigSize + kExtraAllocSize);
  EXPECT_EQ(4u, totalSlots);
  // The freelist should have one entry, because we were able to exactly fit
  // one object slot and one freelist pointer (the null that the head points
  // to) into a system page.
  EXPECT_TRUE(page->freelistHead);
  EXPECT_EQ(1, page->numAllocatedSlots);
  EXPECT_EQ(2, page->numUnprovisionedSlots);

  void* ptr2 = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr2);
  EXPECT_FALSE(page->freelistHead);
  EXPECT_EQ(2, page->numAllocatedSlots);
  EXPECT_EQ(2, page->numUnprovisionedSlots);

  void* ptr3 = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr3);
  EXPECT_TRUE(page->freelistHead);
  EXPECT_EQ(3, page->numAllocatedSlots);
  EXPECT_EQ(0, page->numUnprovisionedSlots);

  void* ptr4 = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr4);
  EXPECT_FALSE(page->freelistHead);
  EXPECT_EQ(4, page->numAllocatedSlots);
  EXPECT_EQ(0, page->numUnprovisionedSlots);

  void* ptr5 = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr5);

  WTF::PartitionPage* page2 =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr5));
  EXPECT_EQ(1, page2->numAllocatedSlots);

  // Churn things a little whilst there's a partial page freelist.
  partitionFree(ptr);
  ptr = partitionAlloc(allocator.root(), bigSize);
  void* ptr6 = partitionAlloc(allocator.root(), bigSize);

  partitionFree(ptr);
  partitionFree(ptr2);
  partitionFree(ptr3);
  partitionFree(ptr4);
  partitionFree(ptr5);
  partitionFree(ptr6);
  EXPECT_NE(-1, page->freeCacheIndex);
  EXPECT_NE(-1, page2->freeCacheIndex);
  EXPECT_TRUE(page2->freelistHead);
  EXPECT_EQ(0, page2->numAllocatedSlots);

  // And test a couple of sizes that do not cross kSystemPageSize with a single
  // allocation.
  size_t mediumSize = (WTF::kSystemPageSize / 2) - kExtraAllocSize;
  bucketIdx = (mediumSize + kExtraAllocSize) >> WTF::kBucketShift;
  bucket = &allocator.root()->buckets()[bucketIdx];
  EXPECT_EQ(0, bucket->freePagesHead);

  ptr = partitionAlloc(allocator.root(), mediumSize);
  EXPECT_TRUE(ptr);
  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);
  totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (mediumSize + kExtraAllocSize);
  size_t firstPageSlots = WTF::kSystemPageSize / (mediumSize + kExtraAllocSize);
  EXPECT_EQ(2u, firstPageSlots);
  EXPECT_EQ(totalSlots - firstPageSlots, page->numUnprovisionedSlots);

  partitionFree(ptr);

  size_t smallSize = (WTF::kSystemPageSize / 4) - kExtraAllocSize;
  bucketIdx = (smallSize + kExtraAllocSize) >> WTF::kBucketShift;
  bucket = &allocator.root()->buckets()[bucketIdx];
  EXPECT_EQ(0, bucket->freePagesHead);

  ptr = partitionAlloc(allocator.root(), smallSize);
  EXPECT_TRUE(ptr);
  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);
  totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (smallSize + kExtraAllocSize);
  firstPageSlots = WTF::kSystemPageSize / (smallSize + kExtraAllocSize);
  EXPECT_EQ(totalSlots - firstPageSlots, page->numUnprovisionedSlots);

  partitionFree(ptr);
  EXPECT_TRUE(page->freelistHead);
  EXPECT_EQ(0, page->numAllocatedSlots);

  size_t verySmallSize = 32 - kExtraAllocSize;
  bucketIdx = (verySmallSize + kExtraAllocSize) >> WTF::kBucketShift;
  bucket = &allocator.root()->buckets()[bucketIdx];
  EXPECT_EQ(0, bucket->freePagesHead);

  ptr = partitionAlloc(allocator.root(), verySmallSize);
  EXPECT_TRUE(ptr);
  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);
  totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (verySmallSize + kExtraAllocSize);
  firstPageSlots = WTF::kSystemPageSize / (verySmallSize + kExtraAllocSize);
  EXPECT_EQ(totalSlots - firstPageSlots, page->numUnprovisionedSlots);

  partitionFree(ptr);
  EXPECT_TRUE(page->freelistHead);
  EXPECT_EQ(0, page->numAllocatedSlots);

  // And try an allocation size (against the generic allocator) that is
  // larger than a system page.
  size_t pageAndAHalfSize =
      (WTF::kSystemPageSize + (WTF::kSystemPageSize / 2)) - kExtraAllocSize;
  ptr = partitionAllocGeneric(genericAllocator.root(), pageAndAHalfSize);
  EXPECT_TRUE(ptr);
  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);
  EXPECT_TRUE(page->freelistHead);
  totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (pageAndAHalfSize + kExtraAllocSize);
  EXPECT_EQ(totalSlots - 2, page->numUnprovisionedSlots);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  // And then make sure than exactly the page size only faults one page.
  size_t pageSize = WTF::kSystemPageSize - kExtraAllocSize;
  ptr = partitionAllocGeneric(genericAllocator.root(), pageSize);
  EXPECT_TRUE(ptr);
  page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);
  EXPECT_FALSE(page->freelistHead);
  totalSlots =
      (page->bucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize) /
      (pageSize + kExtraAllocSize);
  EXPECT_EQ(totalSlots - 1, page->numUnprovisionedSlots);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  TestShutdown();
}

// Test some of the fragmentation-resistant properties of the allocator.
TEST(PartitionAllocTest, PageRefilling) {
  TestSetup();
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[kTestBucketIndex];

  // Grab two full pages and a non-full page.
  WTF::PartitionPage* page1 = GetFullPage(kTestAllocSize);
  WTF::PartitionPage* page2 = GetFullPage(kTestAllocSize);
  void* ptr = partitionAlloc(allocator.root(), kTestAllocSize);
  EXPECT_TRUE(ptr);
  EXPECT_NE(page1, bucket->activePagesHead);
  EXPECT_NE(page2, bucket->activePagesHead);
  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(1, page->numAllocatedSlots);

  // Work out a pointer into page2 and free it; and then page1 and free it.
  char* ptr2 = reinterpret_cast<char*>(WTF::partitionPageToPointer(page1)) +
               kPointerOffset;
  partitionFree(ptr2);
  ptr2 = reinterpret_cast<char*>(WTF::partitionPageToPointer(page2)) +
         kPointerOffset;
  partitionFree(ptr2);

  // If we perform two allocations from the same bucket now, we expect to
  // refill both the nearly full pages.
  (void)partitionAlloc(allocator.root(), kTestAllocSize);
  (void)partitionAlloc(allocator.root(), kTestAllocSize);
  EXPECT_EQ(1, page->numAllocatedSlots);

  FreeFullPage(page2);
  FreeFullPage(page1);
  partitionFree(ptr);

  TestShutdown();
}

// Basic tests to ensure that allocations work for partial page buckets.
TEST(PartitionAllocTest, PartialPages) {
  TestSetup();

  // Find a size that is backed by a partial partition page.
  size_t size = sizeof(void*);
  WTF::PartitionBucket* bucket = 0;
  while (size < kTestMaxAllocation) {
    bucket = &allocator.root()->buckets()[size >> WTF::kBucketShift];
    if (bucket->numSystemPagesPerSlotSpan %
        WTF::kNumSystemPagesPerPartitionPage)
      break;
    size += sizeof(void*);
  }
  EXPECT_LT(size, kTestMaxAllocation);

  WTF::PartitionPage* page1 = GetFullPage(size);
  WTF::PartitionPage* page2 = GetFullPage(size);
  FreeFullPage(page2);
  FreeFullPage(page1);

  TestShutdown();
}

// Test correct handling if our mapping collides with another.
TEST(PartitionAllocTest, MappingCollision) {
  TestSetup();
  // The -2 is because the first and last partition pages in a super page are
  // guard pages.
  size_t numPartitionPagesNeeded = WTF::kNumPartitionPagesPerSuperPage - 2;
  OwnPtr<WTF::PartitionPage* []> firstSuperPagePages =
      adoptArrayPtr(new WTF::PartitionPage*[numPartitionPagesNeeded]);
  OwnPtr<WTF::PartitionPage* []> secondSuperPagePages =
      adoptArrayPtr(new WTF::PartitionPage*[numPartitionPagesNeeded]);

  size_t i;
  for (i = 0; i < numPartitionPagesNeeded; ++i)
    firstSuperPagePages[i] = GetFullPage(kTestAllocSize);

  char* pageBase = reinterpret_cast<char*>(
      WTF::partitionPageToPointer(firstSuperPagePages[0]));
  EXPECT_EQ(WTF::kPartitionPageSize,
            reinterpret_cast<uintptr_t>(pageBase) & WTF::kSuperPageOffsetMask);
  pageBase -= WTF::kPartitionPageSize;
  // Map a single system page either side of the mapping for our allocations,
  // with the goal of tripping up alignment of the next mapping.
  void* map1 = WTF::allocPages(pageBase - WTF::kPageAllocationGranularity,
                               WTF::kPageAllocationGranularity,
                               WTF::kPageAllocationGranularity);
  EXPECT_TRUE(map1);
  void* map2 = WTF::allocPages(pageBase + WTF::kSuperPageSize,
                               WTF::kPageAllocationGranularity,
                               WTF::kPageAllocationGranularity);
  EXPECT_TRUE(map2);
  WTF::setSystemPagesInaccessible(map1, WTF::kPageAllocationGranularity);
  WTF::setSystemPagesInaccessible(map2, WTF::kPageAllocationGranularity);

  for (i = 0; i < numPartitionPagesNeeded; ++i)
    secondSuperPagePages[i] = GetFullPage(kTestAllocSize);

  WTF::freePages(map1, WTF::kPageAllocationGranularity);
  WTF::freePages(map2, WTF::kPageAllocationGranularity);

  pageBase =
      reinterpret_cast<char*>(partitionPageToPointer(secondSuperPagePages[0]));
  EXPECT_EQ(WTF::kPartitionPageSize,
            reinterpret_cast<uintptr_t>(pageBase) & WTF::kSuperPageOffsetMask);
  pageBase -= WTF::kPartitionPageSize;
  // Map a single system page either side of the mapping for our allocations,
  // with the goal of tripping up alignment of the next mapping.
  map1 = WTF::allocPages(pageBase - WTF::kPageAllocationGranularity,
                         WTF::kPageAllocationGranularity,
                         WTF::kPageAllocationGranularity);
  EXPECT_TRUE(map1);
  map2 = WTF::allocPages(pageBase + WTF::kSuperPageSize,
                         WTF::kPageAllocationGranularity,
                         WTF::kPageAllocationGranularity);
  EXPECT_TRUE(map2);
  WTF::setSystemPagesInaccessible(map1, WTF::kPageAllocationGranularity);
  WTF::setSystemPagesInaccessible(map2, WTF::kPageAllocationGranularity);

  WTF::PartitionPage* pageInThirdSuperPage = GetFullPage(kTestAllocSize);
  WTF::freePages(map1, WTF::kPageAllocationGranularity);
  WTF::freePages(map2, WTF::kPageAllocationGranularity);

  EXPECT_EQ(0u, reinterpret_cast<uintptr_t>(
                    partitionPageToPointer(pageInThirdSuperPage)) &
                    WTF::kPartitionPageOffsetMask);

  // And make sure we really did get a page in a new superpage.
  EXPECT_NE(reinterpret_cast<uintptr_t>(
                partitionPageToPointer(firstSuperPagePages[0])) &
                WTF::kSuperPageBaseMask,
            reinterpret_cast<uintptr_t>(
                partitionPageToPointer(pageInThirdSuperPage)) &
                WTF::kSuperPageBaseMask);
  EXPECT_NE(reinterpret_cast<uintptr_t>(
                partitionPageToPointer(secondSuperPagePages[0])) &
                WTF::kSuperPageBaseMask,
            reinterpret_cast<uintptr_t>(
                partitionPageToPointer(pageInThirdSuperPage)) &
                WTF::kSuperPageBaseMask);

  FreeFullPage(pageInThirdSuperPage);
  for (i = 0; i < numPartitionPagesNeeded; ++i) {
    FreeFullPage(firstSuperPagePages[i]);
    FreeFullPage(secondSuperPagePages[i]);
  }

  TestShutdown();
}

// Tests that pages in the free page cache do get freed as appropriate.
TEST(PartitionAllocTest, FreeCache) {
  TestSetup();

  EXPECT_EQ(0U, allocator.root()->totalSizeOfCommittedPages);

  size_t bigSize = allocator.root()->maxAllocation - kExtraAllocSize;
  size_t bucketIdx = (bigSize + kExtraAllocSize) >> WTF::kBucketShift;
  WTF::PartitionBucket* bucket = &allocator.root()->buckets()[bucketIdx];

  void* ptr = partitionAlloc(allocator.root(), bigSize);
  EXPECT_TRUE(ptr);
  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  EXPECT_EQ(0, bucket->freePagesHead);
  EXPECT_EQ(1, page->numAllocatedSlots);
  EXPECT_EQ(WTF::kPartitionPageSize,
            allocator.root()->totalSizeOfCommittedPages);
  partitionFree(ptr);
  EXPECT_EQ(0, page->numAllocatedSlots);
  EXPECT_NE(-1, page->freeCacheIndex);
  EXPECT_TRUE(page->freelistHead);

  CycleFreeCache(kTestAllocSize);

  // Flushing the cache should have really freed the unused page.
  EXPECT_FALSE(page->freelistHead);
  EXPECT_EQ(-1, page->freeCacheIndex);
  EXPECT_EQ(0, page->numAllocatedSlots);
  WTF::PartitionBucket* cycleFreeCacheBucket =
      &allocator.root()->buckets()[kTestBucketIndex];
  EXPECT_EQ(
      cycleFreeCacheBucket->numSystemPagesPerSlotSpan * WTF::kSystemPageSize,
      allocator.root()->totalSizeOfCommittedPages);

  // Check that an allocation works ok whilst in this state (a free'd page
  // as the active pages head).
  ptr = partitionAlloc(allocator.root(), bigSize);
  EXPECT_FALSE(bucket->freePagesHead);
  partitionFree(ptr);

  // Also check that a page that is bouncing immediately between empty and
  // used does not get freed.
  for (size_t i = 0; i < WTF::kMaxFreeableSpans * 2; ++i) {
    ptr = partitionAlloc(allocator.root(), bigSize);
    EXPECT_TRUE(page->freelistHead);
    partitionFree(ptr);
    EXPECT_TRUE(page->freelistHead);
  }
  EXPECT_EQ(WTF::kPartitionPageSize,
            allocator.root()->totalSizeOfCommittedPages);
  TestShutdown();
}

// Tests for a bug we had with losing references to free pages.
TEST(PartitionAllocTest, LostFreePagesBug) {
  TestSetup();

  size_t size = WTF::kPartitionPageSize - kExtraAllocSize;

  void* ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  void* ptr2 = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr2);

  WTF::PartitionPage* page =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr));
  WTF::PartitionPage* page2 =
      WTF::partitionPointerToPage(WTF::partitionCookieFreePointerAdjust(ptr2));
  WTF::PartitionBucket* bucket = page->bucket;

  EXPECT_EQ(0, bucket->freePagesHead);
  EXPECT_EQ(-1, page->numAllocatedSlots);
  EXPECT_EQ(1, page2->numAllocatedSlots);

  partitionFreeGeneric(genericAllocator.root(), ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr2);

  EXPECT_EQ(0, bucket->freePagesHead);
  EXPECT_EQ(0, page->numAllocatedSlots);
  EXPECT_EQ(0, page2->numAllocatedSlots);
  EXPECT_TRUE(page->freelistHead);
  EXPECT_TRUE(page2->freelistHead);

  CycleGenericFreeCache(kTestAllocSize);

  EXPECT_FALSE(page->freelistHead);
  EXPECT_FALSE(page2->freelistHead);

  EXPECT_FALSE(bucket->freePagesHead);
  EXPECT_TRUE(bucket->activePagesHead);
  EXPECT_TRUE(bucket->activePagesHead->nextPage);

  // At this moment, we have two freed pages, on the freelist.

  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  EXPECT_TRUE(bucket->activePagesHead);
  EXPECT_TRUE(bucket->freePagesHead);

  CycleGenericFreeCache(kTestAllocSize);

  // We're now set up to trigger the bug by scanning over the active pages
  // list, where the current active page is freed, and there exists at least
  // one freed page in the free pages list.
  ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  EXPECT_TRUE(bucket->activePagesHead);
  EXPECT_TRUE(bucket->freePagesHead);

  TestShutdown();
}

#if !OS(ANDROID) && !OS(IOS) && !OS(FUCHSIA)

// Make sure that malloc(-1) dies.
// In the past, we had an integer overflow that would alias malloc(-1) to
// malloc(0), which is not good.
TEST(PartitionAllocDeathTest, LargeAllocs) {
  TestSetup();
  // Largest alloc.
  EXPECT_DEATH(
      partitionAllocGeneric(genericAllocator.root(), static_cast<size_t>(-1)),
      "");
  // And the smallest allocation we expect to die.
  EXPECT_DEATH(partitionAllocGeneric(genericAllocator.root(),
                                     static_cast<size_t>(INT_MAX) + 1),
               "");

  TestShutdown();
}

// Check that our immediate double-free detection works.
TEST(PartitionAllocDeathTest, ImmediateDoubleFree) {
  TestSetup();

  void* ptr = partitionAllocGeneric(genericAllocator.root(), kTestAllocSize);
  EXPECT_TRUE(ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr);

  EXPECT_DEATH(partitionFreeGeneric(genericAllocator.root(), ptr), "");

  TestShutdown();
}

// Check that our refcount-based double-free detection works.
TEST(PartitionAllocDeathTest, RefcountDoubleFree) {
  TestSetup();

  void* ptr = partitionAllocGeneric(genericAllocator.root(), kTestAllocSize);
  EXPECT_TRUE(ptr);
  void* ptr2 = partitionAllocGeneric(genericAllocator.root(), kTestAllocSize);
  EXPECT_TRUE(ptr2);
  partitionFreeGeneric(genericAllocator.root(), ptr);
  partitionFreeGeneric(genericAllocator.root(), ptr2);
  // This is not an immediate double-free so our immediate detection won't
  // fire. However, it does take the "refcount" of the partition page to -1,
  // which is illegal and should be trapped.
  EXPECT_DEATH(partitionFreeGeneric(genericAllocator.root(), ptr), "");

  TestShutdown();
}

// Check that guard pages are present where expected.
TEST(PartitionAllocDeathTest, GuardPages) {
  TestSetup();

  // This large size will result in a direct mapped allocation with guard
  // pages at either end.
  size_t size =
      (WTF::kGenericMaxBucketed + WTF::kSystemPageSize) - kExtraAllocSize;
  void* ptr = partitionAllocGeneric(genericAllocator.root(), size);
  EXPECT_TRUE(ptr);
  char* charPtr = reinterpret_cast<char*>(ptr) - kPointerOffset;

  EXPECT_DEATH(*(charPtr - 1) = 'A', "");
  EXPECT_DEATH(*(charPtr + size + kExtraAllocSize) = 'A', "");

  partitionFreeGeneric(genericAllocator.root(), ptr);

  TestShutdown();
}

#endif  // !OS(ANDROID)

// Tests that the countLeadingZeros() functions work to our satisfaction.
// It doesn't seem worth the overhead of a whole new file for these tests, so
// we'll put them here since partitionAllocGeneric will depend heavily on these
// functions working correctly.
TEST(PartitionAllocTest, CLZWorks) {
  EXPECT_EQ(32u, WTF::countLeadingZeros32(0u));
  EXPECT_EQ(31u, WTF::countLeadingZeros32(1u));
  EXPECT_EQ(1u, WTF::countLeadingZeros32(1u << 30));
  EXPECT_EQ(0u, WTF::countLeadingZeros32(1u << 31));

#if CPU(64BIT)
  EXPECT_EQ(64u, WTF::countLeadingZerosSizet(0ull));
  EXPECT_EQ(63u, WTF::countLeadingZerosSizet(1ull));
  EXPECT_EQ(32u, WTF::countLeadingZerosSizet(1ull << 31));
  EXPECT_EQ(1u, WTF::countLeadingZerosSizet(1ull << 62));
  EXPECT_EQ(0u, WTF::countLeadingZerosSizet(1ull << 63));
#else
  EXPECT_EQ(32u, WTF::countLeadingZerosSizet(0u));
  EXPECT_EQ(31u, WTF::countLeadingZerosSizet(1u));
  EXPECT_EQ(1u, WTF::countLeadingZerosSizet(1u << 30));
  EXPECT_EQ(0u, WTF::countLeadingZerosSizet(1u << 31));
#endif
}

}  // namespace

#endif  // !defined(MEMORY_TOOL_REPLACES_ALLOCATOR)