Cashew: implement backend usage API

src/data_plan_provider.cc

+// Copyright (c) 2010 The Chromium OS 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 "src/data_plan_provider.h"
+
+#include <base/json/json_reader.h>
+#include <base/scoped_ptr.h>
+#include <base/values.h>
+#include <glog/logging.h>
+
+#include "src/libcurl_http_fetcher.h"
+
+namespace cashew {
+
+DataPlanProvider::DataPlanProvider(const std::string& carrier)
+    : carrier_(carrier), delegate_(NULL),
+      fetcher_(CHECK_NOTNULL(new(std::nothrow) LibcurlHttpFetcher())),
+      request_in_progress_(false) {
+  fetcher_->set_delegate(this);
+}
+
+DataPlanProvider::~DataPlanProvider() {
+  CancelPendingRequests();
+}
+
+const std::string& DataPlanProvider::GetCarrier() const {
+  return carrier_;
+}
+
+const std::string& DataPlanProvider::GetUsageUrl() const {
+  return usage_url_;
+}
+
+void DataPlanProvider::SetUsageUrl(const std::string& usage_url) {
+  DLOG(INFO) << carrier_ << ": SetUsageUrl: url = " << usage_url;
+  if (usage_url_.compare(usage_url)) {
+    usage_url_ = usage_url;
+    CancelPendingRequests();
+  }
+}
+
+void DataPlanProvider::SetDelegate(DataPlanProviderDelegate *delegate) {
+  DLOG(INFO) << carrier_ << ": SetDelegate";
+  delegate_ = delegate;
+  if (delegate_ == NULL) {
+    CancelPendingRequests();
+  }
+}
+
+bool DataPlanProvider::RequestUsageUpdate() {
+  if (usage_url_.empty()) {
+    DLOG(WARNING) << carrier_ << ": RequestUsageUpdate: no usage url";
+    return false;
+  }
+  if (delegate_ == NULL) {
+    DLOG(WARNING) << carrier_ << ": RequestUsageUpdate: no delegate";
+    return false;
+  }
+  if (request_in_progress_) {
+    DLOG(INFO) << carrier_
+        << ": RequestUsageUpdate: request already in progress";
+    // we'll satisfy this request with the result from the in-flight one
+    return true;
+  }
+  DCHECK(response_buffer_.empty());
+  DLOG(INFO) << carrier_ << ": RequestUsageUpdate: initiating request";
+  request_in_progress_ = true;
+  fetcher_->BeginTransfer(usage_url_);
+  return true;
+}
+
+// HttpFetcherDelegate methods
+
+void DataPlanProvider::ReceivedBytes(HttpFetcher *fetcher, const char *bytes,
+                                     int length) {
+  DCHECK(fetcher != NULL);
+  DCHECK(bytes != NULL);
+  DCHECK_GE(length, 0);
+  if (fetcher != fetcher_) {
+    DLOG(WARNING) << carrier_ << ": ReceivedBytes: wrong fetcher";
+    return;
+  }
+  DCHECK(request_in_progress_);
+  DLOG(INFO) << carrier_ << ": ReceivedBytes: length = " << length;
+  response_buffer_.reserve(response_buffer_.size() + length);
+  response_buffer_.insert(response_buffer_.end(), bytes, bytes + length);
+}
+
+void DataPlanProvider::TransferComplete(HttpFetcher *fetcher,
+                                        bool successful) {
+  DCHECK(fetcher != NULL);
+  if (fetcher != fetcher_) {
+    DLOG(WARNING) << carrier_ << ": TransferComplete: wrong fetcher";
+    return;
+  }
+  DCHECK(request_in_progress_);
+  DCHECK(delegate_ != NULL);
+  DLOG(INFO) << carrier_ << ": TransferComplete: result = " << successful;
+  if (!successful) {
+    LOG(WARNING) << carrier_ << ": TransferComplete: failed: response code = "
+        << fetcher_->http_response_code();
+    response_buffer_.clear();
+    request_in_progress_ = false;
+    delegate_->OnRequestComplete(this, false, NULL);
+    return;
+  }
+  LOG(INFO) << carrier_ << ": TransferComplete: success: response code = "
+      << fetcher_->http_response_code();
+
+  // carrier usage API has (we hope) given us a JSON-encoded result
+  // log it and then parse it, converting it into a tree of Value nodes
+  // TODO(vlaviano): extend JSONReader to handle 64-bit ints
+  const std::string json_encoded_usage_update(response_buffer_.begin(),
+                                              response_buffer_.end());
+  response_buffer_.clear();
+  request_in_progress_ = false;
+
+  LOG(INFO) << carrier_ << ": TransferComplete: response:\n"
+      << json_encoded_usage_update;
+
+  int error_code;
+  std::string error_msg;
+  scoped_ptr<Value> parsed_usage_update(
+      base::JSONReader::ReadAndReturnError(json_encoded_usage_update, true,
+                                           &error_code, &error_msg));
+  if (parsed_usage_update == NULL) {
+    LOG(WARNING) << carrier_ << ": TransferComplete: could not parse json: "
+        << "error code " << error_code << ": " << error_msg;
+    delegate_->OnRequestComplete(this, false, NULL);
+    return;
+  }
+  DLOG(INFO) << carrier_ << ": TransferComplete: successfully parsed json";
+  delegate_->OnRequestComplete(this, true, parsed_usage_update.get());
+}
+
+void DataPlanProvider::CancelPendingRequests() {
+  if (request_in_progress_) {
+    fetcher_->TerminateTransfer();
+    response_buffer_.clear();
+    request_in_progress_ = false;
+  }
+}
+
+// private methods
+
+}  // namespace cashew