mirror of
https://github.com/flutter/flutter.git
synced 2026-02-20 02:29:02 +08:00
103 lines
3.9 KiB
C++
103 lines
3.9 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
#ifndef MOJO_EDK_EMBEDDER_PLATFORM_SHARED_BUFFER_H_
|
|
#define MOJO_EDK_EMBEDDER_PLATFORM_SHARED_BUFFER_H_
|
|
|
|
#include <stddef.h>
|
|
|
|
#include "base/memory/ref_counted.h"
|
|
#include "base/memory/scoped_ptr.h"
|
|
#include "mojo/edk/embedder/scoped_platform_handle.h"
|
|
#include "mojo/edk/system/system_impl_export.h"
|
|
#include "mojo/public/cpp/system/macros.h"
|
|
|
|
namespace mojo {
|
|
namespace embedder {
|
|
|
|
class PlatformSharedBufferMapping;
|
|
|
|
// |PlatformSharedBuffer| is an interface for a thread-safe, ref-counted wrapper
|
|
// around OS-specific shared memory. It has the following features:
|
|
// - A |PlatformSharedBuffer| simply represents a piece of shared memory that
|
|
// *may* be mapped and *may* be shared to another process.
|
|
// - A single |PlatformSharedBuffer| may be mapped multiple times. The
|
|
// lifetime of the mapping (owned by |PlatformSharedBufferMapping|) is
|
|
// separate from the lifetime of the |PlatformSharedBuffer|.
|
|
// - Sizes/offsets (of the shared memory and mappings) are arbitrary, and not
|
|
// restricted by page size. However, more memory may actually be mapped than
|
|
// requested.
|
|
//
|
|
// It currently does NOT support the following:
|
|
// - Sharing read-only. (This will probably eventually be supported.)
|
|
//
|
|
// TODO(vtl): Rectify this with |base::SharedMemory|.
|
|
class MOJO_SYSTEM_IMPL_EXPORT PlatformSharedBuffer
|
|
: public base::RefCountedThreadSafe<PlatformSharedBuffer> {
|
|
public:
|
|
// Gets the size of shared buffer (in number of bytes).
|
|
virtual size_t GetNumBytes() const = 0;
|
|
|
|
// Maps (some) of the shared buffer into memory; [|offset|, |offset + length|]
|
|
// must be contained in [0, |num_bytes|], and |length| must be at least 1.
|
|
// Returns null on failure.
|
|
virtual scoped_ptr<PlatformSharedBufferMapping> Map(size_t offset,
|
|
size_t length) = 0;
|
|
|
|
// Checks if |offset| and |length| are valid arguments.
|
|
virtual bool IsValidMap(size_t offset, size_t length) = 0;
|
|
|
|
// Like |Map()|, but doesn't check its arguments (which should have been
|
|
// preflighted using |IsValidMap()|).
|
|
virtual scoped_ptr<PlatformSharedBufferMapping> MapNoCheck(size_t offset,
|
|
size_t length) = 0;
|
|
|
|
// Duplicates the underlying platform handle and passes it to the caller.
|
|
// TODO(vtl): On POSIX, we'll need two FDs to support sharing read-only.
|
|
virtual ScopedPlatformHandle DuplicatePlatformHandle() = 0;
|
|
|
|
// Passes the underlying platform handle to the caller. This should only be
|
|
// called if there's a unique reference to this object (owned by the caller).
|
|
// After calling this, this object should no longer be used, but should only
|
|
// be disposed of.
|
|
virtual ScopedPlatformHandle PassPlatformHandle() = 0;
|
|
|
|
protected:
|
|
friend class base::RefCountedThreadSafe<PlatformSharedBuffer>;
|
|
|
|
PlatformSharedBuffer() {}
|
|
virtual ~PlatformSharedBuffer() {}
|
|
|
|
private:
|
|
MOJO_DISALLOW_COPY_AND_ASSIGN(PlatformSharedBuffer);
|
|
};
|
|
|
|
// An interface for a mapping of a |PlatformSharedBuffer| (compararable to a
|
|
// "file view" in Windows); see above. Created by (implementations of)
|
|
// |PlatformSharedBuffer::Map()|. Automatically unmaps memory on destruction.
|
|
//
|
|
// Mappings are NOT thread-safe.
|
|
//
|
|
// Note: This is an entirely separate class (instead of
|
|
// |PlatformSharedBuffer::Mapping|) so that it can be forward-declared.
|
|
class MOJO_SYSTEM_IMPL_EXPORT PlatformSharedBufferMapping {
|
|
public:
|
|
// IMPORTANT: Implementations must implement a destructor that unmaps memory.
|
|
virtual ~PlatformSharedBufferMapping() {}
|
|
|
|
virtual void* GetBase() const = 0;
|
|
virtual size_t GetLength() const = 0;
|
|
|
|
protected:
|
|
PlatformSharedBufferMapping() {}
|
|
|
|
private:
|
|
MOJO_DISALLOW_COPY_AND_ASSIGN(PlatformSharedBufferMapping);
|
|
};
|
|
|
|
} // namespace embedder
|
|
} // namespace mojo
|
|
|
|
#endif // MOJO_EDK_EMBEDDER_PLATFORM_SHARED_BUFFER_H_
|