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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
* Copyright (C) 2012, 2014 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "AsyncFileStream.h"
#include "FileStream.h"
#include "FileStreamClient.h"
#include "URL.h"
#include <mutex>
#include <wtf/AutodrainedPool.h>
#include <wtf/Function.h>
#include <wtf/MainThread.h>
#include <wtf/MessageQueue.h>
#include <wtf/NeverDestroyed.h>
namespace WebCore {
struct AsyncFileStream::Internals {
explicit Internals(FileStreamClient&);
FileStream stream;
FileStreamClient& client;
#if !COMPILER(MSVC)
std::atomic_bool destroyed { false };
#else
std::atomic_bool destroyed;
#endif
};
inline AsyncFileStream::Internals::Internals(FileStreamClient& client)
: client(client)
{
#if COMPILER(MSVC)
// Work around a bug that prevents the default value above from compiling.
atomic_init(&destroyed, false);
#endif
}
static void callOnFileThread(Function<void ()>&& function)
{
ASSERT(isMainThread());
ASSERT(function);
static NeverDestroyed<MessageQueue<Function<void ()>>> queue;
static std::once_flag createFileThreadOnce;
std::call_once(createFileThreadOnce, [] {
createThread("WebCore: AsyncFileStream", [] {
for (;;) {
AutodrainedPool pool;
auto function = queue.get().waitForMessage();
// This can never be null because we never kill the MessageQueue.
ASSERT(function);
// This can bever be null because we never queue a function that is null.
ASSERT(*function);
(*function)();
}
});
});
queue.get().append(std::make_unique<Function<void ()>>(WTFMove(function)));
}
AsyncFileStream::AsyncFileStream(FileStreamClient& client)
: m_internals(std::make_unique<Internals>(client))
{
ASSERT(isMainThread());
}
AsyncFileStream::~AsyncFileStream()
{
ASSERT(isMainThread());
// Set flag to prevent client callbacks and also prevent queued operations from starting.
m_internals->destroyed = true;
// Call through file thread and back to main thread to make sure deletion happens
// after all file thread functions and all main thread functions called from them.
callOnFileThread([internals = WTFMove(m_internals)]() mutable {
callOnMainThread([internals = WTFMove(internals)] {
});
});
}
void AsyncFileStream::perform(Function<std::function<void(FileStreamClient&)>(FileStream&)>&& operation)
{
auto& internals = *m_internals;
callOnFileThread([&internals, operation = WTFMove(operation)] {
// Don't do the operation if stop was already called on the main thread. Note that there is
// a race here, but since skipping the operation is an optimization it's OK that we can't
// guarantee exactly which operations are skipped. Note that this is also the only reason
// we use an atomic_bool rather than just a bool for destroyed.
if (internals.destroyed)
return;
callOnMainThread([&internals, mainThreadWork = operation(internals.stream)] {
if (internals.destroyed)
return;
mainThreadWork(internals.client);
});
});
}
void AsyncFileStream::getSize(const String& path, double expectedModificationTime)
{
// FIXME: Explicit return type here and in all the other cases like this below is a workaround for a deficiency
// in the Windows compiler at the time of this writing. Could remove it if that is resolved.
perform([path = path.isolatedCopy(), expectedModificationTime](FileStream& stream) -> std::function<void(FileStreamClient&)> {
long long size = stream.getSize(path, expectedModificationTime);
return [size](FileStreamClient& client) {
client.didGetSize(size);
};
});
}
void AsyncFileStream::openForRead(const String& path, long long offset, long long length)
{
// FIXME: Explicit return type here is a workaround for a deficiency in the Windows compiler at the time of this writing.
perform([path = path.isolatedCopy(), offset, length](FileStream& stream) -> std::function<void(FileStreamClient&)> {
bool success = stream.openForRead(path, offset, length);
return [success](FileStreamClient& client) {
client.didOpen(success);
};
});
}
void AsyncFileStream::close()
{
auto& internals = *m_internals;
callOnFileThread([&internals] {
internals.stream.close();
});
}
void AsyncFileStream::read(char* buffer, int length)
{
perform([buffer, length](FileStream& stream) -> std::function<void(FileStreamClient&)> {
int bytesRead = stream.read(buffer, length);
return [bytesRead](FileStreamClient& client) {
client.didRead(bytesRead);
};
});
}
} // namespace WebCore
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