content/child/fileapi/webfilewriter_base.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/child/fileapi/webfilewriter_base.h"
   6
   7 #include "base/logging.h"
   8 #include "third_party/WebKit/public/platform/WebFileError.h"
   9 #include "third_party/WebKit/public/platform/WebFileWriterClient.h"
  10 #include "third_party/WebKit/public/platform/WebURL.h"
  11 #include "webkit/common/fileapi/file_system_util.h"
  12
  13 using storage::FileErrorToWebFileError;
  14
  15 namespace content {
  16
  17 WebFileWriterBase::WebFileWriterBase(const GURL& path,
  18                                      blink::WebFileWriterClient* client)
  19     : path_(path),
  20       client_(client),
  21       operation_(kOperationNone),
  22       cancel_state_(kCancelNotInProgress) {}
  23
  24 WebFileWriterBase::~WebFileWriterBase() {}
  25
  26 void WebFileWriterBase::truncate(long long length) {
  27   DCHECK(kOperationNone == operation_);
  28   DCHECK(kCancelNotInProgress == cancel_state_);
  29   operation_ = kOperationTruncate;
  30   DoTruncate(path_, length);
  31 }
  32
  33 void WebFileWriterBase::write(
  34       long long position,
  35       const blink::WebString& id) {
  36   DCHECK_EQ(kOperationNone, operation_);
  37   DCHECK_EQ(kCancelNotInProgress, cancel_state_);
  38   operation_ = kOperationWrite;
  39   DoWrite(path_, id.utf8(), position);
  40 }
  41
  42 // When we cancel a write/truncate, we always get back the result of the write
  43 // before the result of the cancel, no matter what happens.
  44 // So we'll get back either
  45 //   success [of the write/truncate, in a DidWrite(XXX, true)/DidSucceed() call]
  46 //     followed by failure [of the cancel]; or
  47 //   failure [of the write, either from cancel or other reasons] followed by
  48 //     the result of the cancel.
  49 // In the write case, there could also be queued up non-terminal DidWrite calls
  50 // before any of that comes back, but there will always be a terminal write
  51 // response [success or failure] after them, followed by the cancel result, so
  52 // we can ignore non-terminal write responses, take the terminal write success
  53 // or the first failure as the last write response, then know that the next
  54 // thing to come back is the cancel response.  We only notify the
  55 // AsyncFileWriterClient when it's all over.
  56 void WebFileWriterBase::cancel() {
  57   // Check for the cancel passing the previous operation's return in-flight.
  58   if (kOperationWrite != operation_ && kOperationTruncate != operation_)
  59     return;
  60   if (kCancelNotInProgress != cancel_state_)
  61     return;
  62   cancel_state_ = kCancelSent;
  63   DoCancel();
  64 }
  65
  66 void WebFileWriterBase::DidFinish(base::File::Error error_code) {
  67   if (error_code == base::File::FILE_OK)
  68     DidSucceed();
  69   else
  70     DidFail(error_code);
  71 }
  72
  73 void WebFileWriterBase::DidWrite(int64 bytes, bool complete) {
  74   DCHECK(kOperationWrite == operation_);
  75   switch (cancel_state_) {
  76     case kCancelNotInProgress:
  77       if (complete)
  78         operation_ = kOperationNone;
  79       client_->didWrite(bytes, complete);
  80       break;
  81     case kCancelSent:
  82       // This is the success call of the write, which we'll eat, even though
  83       // it succeeded before the cancel got there.  We accepted the cancel call,
  84       // so the write will eventually return an error.
  85       if (complete)
  86         cancel_state_ = kCancelReceivedWriteResponse;
  87       break;
  88     case kCancelReceivedWriteResponse:
  89     default:
  90       NOTREACHED();
  91   }
  92 }
  93
  94 void WebFileWriterBase::DidSucceed() {
  95   // Write never gets a DidSucceed call, so this is either a cancel or truncate
  96   // response.
  97   switch (cancel_state_) {
  98     case kCancelNotInProgress:
  99       // A truncate succeeded, with no complications.
 100       DCHECK(kOperationTruncate == operation_);
 101       operation_ = kOperationNone;
 102       client_->didTruncate();
 103       break;
 104     case kCancelSent:
 105       DCHECK(kOperationTruncate == operation_);
 106       // This is the success call of the truncate, which we'll eat, even though
 107       // it succeeded before the cancel got there.  We accepted the cancel call,
 108       // so the truncate will eventually return an error.
 109       cancel_state_ = kCancelReceivedWriteResponse;
 110       break;
 111     case kCancelReceivedWriteResponse:
 112       // This is the success of the cancel operation.
 113       FinishCancel();
 114       break;
 115     default:
 116       NOTREACHED();
 117   }
 118 }
 119
 120 void WebFileWriterBase::DidFail(base::File::Error error_code) {
 121   DCHECK(kOperationNone != operation_);
 122   switch (cancel_state_) {
 123     case kCancelNotInProgress:
 124       // A write or truncate failed.
 125       operation_ = kOperationNone;
 126       client_->didFail(FileErrorToWebFileError(error_code));
 127       break;
 128     case kCancelSent:
 129       // This is the failure of a write or truncate; the next message should be
 130       // the result of the cancel.  We don't assume that it'll be a success, as
 131       // the write/truncate could have failed for other reasons.
 132       cancel_state_ = kCancelReceivedWriteResponse;
 133       break;
 134     case kCancelReceivedWriteResponse:
 135       // The cancel reported failure, meaning that the write or truncate
 136       // finished before the cancel got there.  But we suppressed the
 137       // write/truncate's response, and will now report that it was cancelled.
 138       FinishCancel();
 139       break;
 140     default:
 141       NOTREACHED();
 142   }
 143 }
 144
 145 void WebFileWriterBase::FinishCancel() {
 146   DCHECK(kCancelReceivedWriteResponse == cancel_state_);
 147   DCHECK(kOperationNone != operation_);
 148   cancel_state_ = kCancelNotInProgress;
 149   operation_ = kOperationNone;
 150   client_->didFail(blink::WebFileErrorAbort);
 151 }
 152
 153 }  // namespace content