Disk cache: Switch the disk cache to use the cache_thread....

net/disk_cache/in_flight_io.cc

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2010 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.
 
-#include "net/disk_cache/file.h"
-
-#include <fcntl.h>
-
-#include <set>
+#include "net/disk_cache/in_flight_io.h"
 
 #include "base/logging.h"
-#include "base/message_loop.h"
-#include "base/singleton.h"
-#include "base/waitable_event.h"
-#include "base/worker_pool.h"
-#include "net/disk_cache/disk_cache.h"
 
-namespace {
+namespace disk_cache {
 
-class InFlightIO;
-
-// This class represents a single asynchronous IO operation while it is being
-// bounced between threads.
-class BackgroundIO : public base::RefCountedThreadSafe<BackgroundIO> {
- public:
-  // Other than the actual parameters for the IO operation (including the
-  // |callback| that must be notified at the end), we need the controller that
-  // is keeping track of all operations. When done, we notify the controller
-  // (we do NOT invoke the callback), in the worker thead that completed the
-  // operation.
-  BackgroundIO(disk_cache::File* file, const void* buf, size_t buf_len,
-               size_t offset, disk_cache::FileIOCallback* callback,
-               InFlightIO* controller)
-      : io_completed_(true, false), callback_(callback), file_(file), buf_(buf),
-        buf_len_(buf_len), offset_(offset), controller_(controller),
-        bytes_(0) {}
-
-  // Read and Write are the operations that can be performed asynchronously.
-  // The actual parameters for the operation are setup in the constructor of
-  // the object, with the exception of |delete_buffer|, that allows a write
-  // without a callback. Both methods should be called from a worker thread, by
-  // posting a task to the WorkerPool (they are RunnableMethods). When finished,
-  // controller->OnIOComplete() is called.
-  void Read();
-  void Write(bool delete_buffer);
-
-  // This method signals the controller that this operation is finished, in the
-  // original thread (presumably the IO-Thread). In practice, this is a
-  // RunableMethod that allows cancellation.
-  void OnIOSignalled();
-
-  // Allows the cancellation of the task to notify the controller (step number 7
-  // in the diagram below). In practice, if the controller waits for the
-  // operation to finish it doesn't have to wait for the final task to be
-  // processed by the message loop so calling this method prevents its delivery.
-  // Note that this method is not intended to cancel the actual IO operation or
-  // to prevent the first notification to take place (OnIOComplete).
-  void Cancel();
-
-  // Retrieves the number of bytes transfered.
-  int Result();
-
-  base::WaitableEvent* io_completed() {
-    return &io_completed_;
-  }
-
-  disk_cache::FileIOCallback* callback() {
-    return callback_;
-  }
-
-  disk_cache::File* file() {
-    return file_;
-  }
-
- private:
-  friend class base::RefCountedThreadSafe<BackgroundIO>;
-  ~BackgroundIO() {}
-
-  // An event to signal when the operation completes, and the user callback that
-  // has to be invoked. These members are accessed directly by the controller.
-  base::WaitableEvent io_completed_;
-  disk_cache::FileIOCallback* callback_;
-
-  disk_cache::File* file_;
-  const void* buf_;
-  size_t buf_len_;
-  size_t offset_;
-  InFlightIO* controller_;  // The controller that tracks all operations.
-  int bytes_;  // Final operation result.
-
-  DISALLOW_COPY_AND_ASSIGN(BackgroundIO);
-};
-
-// This class keeps track of every asynchronous IO operation. A single instance
-// of this class is meant to be used to start an asynchronous operation (using
-// PostRead/PostWrite). This class will post the operation to a worker thread,
-// hanlde the notification when the operation finishes and perform the callback
-// on the same thread that was used to start the operation.
-//
-// The regular sequence of calls is:
-//                 Thread_1                          Worker_thread
-//    1.     InFlightIO::PostRead()
-//    2.                         -> PostTask ->
-//    3.                                          BackgroundIO::Read()
-//    4.                                         IO operation completes
-//    5.                                       InFlightIO::OnIOComplete()
-//    6.                         <- PostTask <-
-//    7.  BackgroundIO::OnIOSignalled()
-//    8.  InFlightIO::InvokeCallback()
-//    9.       invoke callback
-//
-// Shutdown is a special case that is handled though WaitForPendingIO() instead
-// of just waiting for step 7.
-class InFlightIO {
- public:
-  InFlightIO() : callback_thread_(MessageLoop::current()) {}
-  ~InFlightIO() {}
-
-  // These methods start an asynchronous operation. The arguments have the same
-  // semantics of the File asynchronous operations, with the exception that the
-  // operation never finishes synchronously.
-  void PostRead(disk_cache::File* file, void* buf, size_t buf_len,
-                size_t offset, disk_cache::FileIOCallback* callback);
-  void PostWrite(disk_cache::File* file, const void* buf, size_t buf_len,
-                 size_t offset, disk_cache::FileIOCallback* callback,
-                 bool delete_buffer);
-
-  // Blocks the current thread until all IO operations tracked by this object
-  // complete.
-  void WaitForPendingIO();
-
-  // Called on a worker thread when |operation| completes.
-  void OnIOComplete(BackgroundIO* operation);
-
-  // Invokes the users' completion callback at the end of the IO operation.
-  // |cancel_task| is true if the actual task posted to the thread is still
-  // queued (because we are inside WaitForPendingIO), and false if said task is
-  // the one performing the call.
-  void InvokeCallback(BackgroundIO* operation, bool cancel_task);
-
- private:
-  typedef std::set<scoped_refptr<BackgroundIO> > IOList;
-
-  IOList io_list_;  // List of pending io operations.
-  MessageLoop* callback_thread_;
-};
-
-// ---------------------------------------------------------------------------
-
-// Runs on a worker thread.
-void BackgroundIO::Read() {
-  if (file_->Read(const_cast<void*>(buf_), buf_len_, offset_)) {
-    bytes_ = static_cast<int>(buf_len_);
-  } else {
-    bytes_ = -1;
-  }
-  controller_->OnIOComplete(this);
-}
-
-int BackgroundIO::Result() {
-  return bytes_;
+// Runs on the IO thread.
+void BackgroundIO::OnIOSignalled() {
+  if (controller_)
+    controller_->InvokeCallback(this, false);
 }
 
 void BackgroundIO::Cancel() {
   DCHECK(controller_);
   controller_ = NULL;
 }
 
-// Runs on a worker thread.
-void BackgroundIO::Write(bool delete_buffer) {
-  bool rv = file_->Write(buf_, buf_len_, offset_);
-  if (delete_buffer) {
-    // TODO(rvargas): remove or update this code.
-    delete[] reinterpret_cast<const char*>(buf_);
-  }
-
-  bytes_ = rv ? static_cast<int>(buf_len_) : -1;
+// Runs on the background thread.
+void BackgroundIO::NotifyController() {
   controller_->OnIOComplete(this);
 }
 
-// Runs on the IO thread.
-void BackgroundIO::OnIOSignalled() {
-  if (controller_)
-    controller_->InvokeCallback(this, false);
-}
-
 // ---------------------------------------------------------------------------
 
-void InFlightIO::PostRead(disk_cache::File *file, void* buf, size_t buf_len,
-                          size_t offset, disk_cache::FileIOCallback *callback) {
-  scoped_refptr<BackgroundIO> operation =
-      new BackgroundIO(file, buf, buf_len, offset, callback, this);
-  io_list_.insert(operation.get());
-  file->AddRef();  // Balanced on InvokeCallback()
-
-  WorkerPool::PostTask(FROM_HERE,
-                       NewRunnableMethod(operation.get(), &BackgroundIO::Read),
-                       true);
-}
-
-void InFlightIO::PostWrite(disk_cache::File* file, const void* buf,
-                           size_t buf_len, size_t offset,
-                           disk_cache::FileIOCallback* callback,
-                           bool delete_buffer) {
-  scoped_refptr<BackgroundIO> operation =
-      new BackgroundIO(file, buf, buf_len, offset, callback, this);
-  io_list_.insert(operation.get());
-  file->AddRef();  // Balanced on InvokeCallback()
-
-  WorkerPool::PostTask(FROM_HERE,
-                       NewRunnableMethod(operation.get(), &BackgroundIO::Write,
-                                         delete_buffer),
-                       true);
-}
-
 void InFlightIO::WaitForPendingIO() {
   while (!io_list_.empty()) {
     // Block the current thread until all pending IO completes.
     IOList::iterator it = io_list_.begin();
     InvokeCallback(*it, true);
   }
 }
 
-// Runs on a worker thread.
+// Runs on a background thread.
 void InFlightIO::OnIOComplete(BackgroundIO* operation) {
   callback_thread_->PostTask(FROM_HERE,
                              NewRunnableMethod(operation,
                                                &BackgroundIO::OnIOSignalled));
   operation->io_completed()->Signal();
 }
 
 // Runs on the IO thread.
 void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
   operation->io_completed()->Wait();
 
   if (cancel_task)
     operation->Cancel();
 
-  disk_cache::FileIOCallback* callback = operation->callback();
-  int bytes = operation->Result();
-
-  // Release the references acquired in PostRead / PostWrite.
-  operation->file()->Release();
+  // Make sure that we remove the operation from the list before invoking the
+  // callback (so that a subsequent cancel does not invoke the callback again).
+  DCHECK(io_list_.find(operation) != io_list_.end());
   io_list_.erase(operation);
-  callback->OnFileIOComplete(bytes);
+  OnOperationComplete(operation, cancel_task);
 }
 
-}  // namespace
-
-namespace disk_cache {
-
-File::File(base::PlatformFile file)
-    : init_(true), mixed_(true), platform_file_(file) {
-}
-
-bool File::Init(const FilePath& name) {
-  if (init_)
-    return false;
-
-  int flags = base::PLATFORM_FILE_OPEN |
-              base::PLATFORM_FILE_READ |
-              base::PLATFORM_FILE_WRITE;
-  platform_file_ = base::CreatePlatformFile(name, flags, NULL);
-  if (platform_file_ < 0) {
-    platform_file_ = 0;
-    return false;
-  }
-
-  init_ = true;
-  return true;
-}
-
-File::~File() {
-  if (platform_file_)
-    close(platform_file_);
-}
-
-base::PlatformFile File::platform_file() const {
-  return platform_file_;
-}
-
-bool File::IsValid() const {
-  if (!init_)
-    return false;
-  return (base::kInvalidPlatformFileValue != platform_file_);
-}
-
-bool File::Read(void* buffer, size_t buffer_len, size_t offset) {
-  DCHECK(init_);
-  if (buffer_len > ULONG_MAX || offset > LONG_MAX)
-    return false;
-
-  int ret = pread(platform_file_, buffer, buffer_len, offset);
-  return (static_cast<size_t>(ret) == buffer_len);
-}
-
-bool File::Write(const void* buffer, size_t buffer_len, size_t offset) {
-  DCHECK(init_);
-  if (buffer_len > ULONG_MAX || offset > ULONG_MAX)
-    return false;
-
-  int ret = pwrite(platform_file_, buffer, buffer_len, offset);
-  return (static_cast<size_t>(ret) == buffer_len);
-}
-
-// We have to increase the ref counter of the file before performing the IO to
-// prevent the completion to happen with an invalid handle (if the file is
-// closed while the IO is in flight).
-bool File::Read(void* buffer, size_t buffer_len, size_t offset,
-                FileIOCallback* callback, bool* completed) {
-  DCHECK(init_);
-  if (!callback) {
-    if (completed)
-      *completed = true;
-    return Read(buffer, buffer_len, offset);
-  }
-
-  if (buffer_len > ULONG_MAX || offset > ULONG_MAX)
-    return false;
-
-  InFlightIO* io_operations = Singleton<InFlightIO>::get();
-  io_operations->PostRead(this, buffer, buffer_len, offset, callback);
-
-  *completed = false;
-  return true;
-}
-
-bool File::Write(const void* buffer, size_t buffer_len, size_t offset,
-                 FileIOCallback* callback, bool* completed) {
-  DCHECK(init_);
-  if (!callback) {
-    if (completed)
-      *completed = true;
-    return Write(buffer, buffer_len, offset);
-  }
-
-  return AsyncWrite(buffer, buffer_len, offset, true, callback, completed);
-}
-
-bool File::PostWrite(const void* buffer, size_t buffer_len, size_t offset) {
-  DCHECK(init_);
-  return AsyncWrite(buffer, buffer_len, offset, false, NULL, NULL);
-}
-
-bool File::AsyncWrite(const void* buffer, size_t buffer_len, size_t offset,
-                      bool notify, FileIOCallback* callback, bool* completed) {
-  DCHECK(init_);
-  if (buffer_len > ULONG_MAX || offset > ULONG_MAX)
-    return false;
-
-  InFlightIO* io_operations = Singleton<InFlightIO>::get();
-  io_operations->PostWrite(this, buffer, buffer_len, offset, callback, !notify);
-
-  if (completed)
-    *completed = false;
-  return true;
-}
-
-bool File::SetLength(size_t length) {
-  DCHECK(init_);
-  if (length > ULONG_MAX)
-    return false;
-
-  return 0 == ftruncate(platform_file_, length);
-}
-
-size_t File::GetLength() {
-  DCHECK(init_);
-  size_t ret = lseek(platform_file_, 0, SEEK_END);
-  return ret;
-}
-
-// Static.
-void File::WaitForPendingIO(int* num_pending_io) {
-  if (*num_pending_io)
-    Singleton<InFlightIO>::get()->WaitForPendingIO();
+// Runs on the IO thread.
+void InFlightIO::OnOperationPosted(BackgroundIO* operation) {
+  io_list_.insert(operation);
 }
 
 }  // namespace disk_cache