DevTools: provide an option to return traces as streams

content/browser/devtools/devtools_io_context.cc

+// Copyright 2015 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 "content/browser/devtools/devtools_io_context.h"
+
+#include "base/files/file.h"
+#include "base/files/file_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/third_party/icu/icu_utf.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+namespace devtools {
+
+namespace {
+unsigned s_last_stream_id = 0;
+}
+
+using Stream = DevToolsIOContext::Stream;
+
+Stream::Stream()
+    : base::RefCountedDeleteOnMessageLoop<Stream>(
+          BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE)),
+      id_(base::IntToString(++s_last_stream_id)),
+      had_errors_(false),
+      last_read_pos_(0) {}
+
+Stream::~Stream() {
+  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+}
+
+bool Stream::InitOnFileThreadIdNeeded() {
+  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  if (had_errors_)
+    return false;
+  if (file_.IsValid())
+    return true;
+  base::FilePath temp_path;
+  if (!base::CreateTemporaryFile(&temp_path)) {
+    LOG(ERROR) << "Failed to create temporary file";
+    had_errors_ = true;
+    return false;
+  }
+  const unsigned flags = base::File::FLAG_OPEN_TRUNCATED |
+                         base::File::FLAG_APPEND | base::File::FLAG_READ |
+                         base::File::FLAG_DELETE_ON_CLOSE;
+  file_.Initialize(temp_path, flags);
+  if (!file_.IsValid()) {
+    LOG(ERROR) << "Failed to open temporary file: " << temp_path.value()
+        << ", " << base::File::ErrorToString(file_.error_details());
+    had_errors_ = true;
+    DeleteFile(temp_path, false);
+    return false;
+  }
+  return true;
+}
+
+void Stream::Read(off_t position, size_t max_size, ReadCallback callback) {

[pfeldman, 2015/08/24 18:17:55]

DCHECK file thread, also don't call on main thread.

+  Status status = StatusFailure;
+  scoped_refptr<base::RefCountedString> data;
+
+  if (file_.IsValid()) {
+    std::string buffer;
+    buffer.resize(max_size);
+    if (position < 0)
+      position = last_read_pos_;
+    int size_got = file_.ReadNoBestEffort(position, &*buffer.begin(), max_size);
+    if (size_got < 0) {
+      LOG(ERROR) << "Failed to read temporary file";
+      had_errors_ = true;
+      file_.Close();
+    } else {
+      // Provided client has requested sufficient large block, make their
+      // life easier by not truncating in the middle of a UTF-8 character.
+      if (size_got > 6 && !CBU8_IS_SINGLE(buffer[size_got - 1])) {
+        base::TruncateUTF8ToByteSize(buffer, size_got, &buffer);
+        size_got = buffer.size();
+      } else {
+        buffer.resize(size_got);
+      }
+      data = base::RefCountedString::TakeString(&buffer);
+      status = size_got ? StatusSuccess : StatusEOF;
+      last_read_pos_ = position + size_got;
+    }
+  }
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                          base::Bind(callback, data, status));
+}
+
+void Stream::Append(const scoped_refptr<base::RefCountedString>& data) {
+  if (!InitOnFileThreadIdNeeded())
+    return;
+  const std::string& buffer = data->data();
+  int size_written = file_.WriteAtCurrentPos(&*buffer.begin(), buffer.size());
+  if (size_written != static_cast<int>(buffer.size())) {
+    LOG(ERROR) << "Failed to write temporary file";
+    had_errors_ = true;
+    file_.Close();
+  }
+}
+
+DevToolsIOContext::DevToolsIOContext() {}
+
+DevToolsIOContext::~DevToolsIOContext() {}
+
+scoped_refptr<Stream> DevToolsIOContext::CreateTempFileBackedStream() {
+  scoped_refptr<Stream> result = new Stream();
+  bool inserted = streams_.insert(std::make_pair(result->id(), result)).second;
+  DCHECK(inserted);
+  return result;
+}
+
+scoped_refptr<Stream> DevToolsIOContext::GetById(const std::string& id) {
+  StreamsMap::const_iterator it = streams_.find(id);
+  return it == streams_.end() ? scoped_refptr<Stream>() : it->second;
+}
+
+bool DevToolsIOContext::Close(const std::string& id) {
+  return streams_.erase(id) == 1;
+}
+
+void DevToolsIOContext::DiscardAllStreams() {
+  return streams_.clear();
+}
+
+}  // namespace devtools
+}  // namespace content