[AiS] ImageService

chrome/browser/bitmap_fetcher/bitmap_fetcher_service.cc

+// Copyright 2014 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 "chrome/browser/bitmap_fetcher/bitmap_fetcher_service.h"
+
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/bitmap_fetcher/bitmap_fetcher.h"
+#include "chrome/browser/profiles/profile.h"
+#include "net/base/load_flags.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace {
+
+const size_t kMaxRequests = 25;  // Maximum number of inflight requests allowed.
+const int kMaxCacheEntries = 5;  // Maximum number of cache entries.
+
+}  // namespace.
+
+class BitmapFetcherRequest {
+ public:
+  BitmapFetcherRequest(BitmapFetcherService::RequestId request_id,
+                       BitmapFetcherService::Observer* observer);
+  ~BitmapFetcherRequest();
+
+  void NotifyImageChanged(const SkBitmap& bitmap);
+  BitmapFetcherService::RequestId request_id() const { return request_id_; }
+
+  // Weak ptr |fetcher| is used to identify associated fetchers.
+  void set_fetcher(const chrome::BitmapFetcher* fetcher) { fetcher_ = fetcher; }
+  const chrome::BitmapFetcher* get_fetcher() const { return fetcher_; }
+
+ private:
+  const BitmapFetcherService::RequestId request_id_;
+  scoped_ptr<BitmapFetcherService::Observer> observer_;
+  const chrome::BitmapFetcher* fetcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(BitmapFetcherRequest);
+};
+
+BitmapFetcherRequest::BitmapFetcherRequest(
+    BitmapFetcherService::RequestId request_id,
+    BitmapFetcherService::Observer* observer)
+    : request_id_(request_id), observer_(observer) {
+}
+
+BitmapFetcherRequest::~BitmapFetcherRequest() {
+  SkBitmap empty_bitmap;
+
+  // OnImageChanged with an empty bitmap signifies a completed request.
+  observer_->OnImageChanged(request_id_, empty_bitmap);
+}
+
+void BitmapFetcherRequest::NotifyImageChanged(const SkBitmap& bitmap) {
+  if (!bitmap.empty())
+    observer_->OnImageChanged(request_id_, bitmap);
+}
+
+BitmapFetcherService::CacheEntry::CacheEntry() {
+}
+
+BitmapFetcherService::CacheEntry::~CacheEntry() {
+}
+
+BitmapFetcherService::BitmapFetcherService(content::BrowserContext* context)
+    : cache_(kMaxCacheEntries), current_request_id_(1), context_(context) {
+}
+
+BitmapFetcherService::~BitmapFetcherService() {
+}
+
+void BitmapFetcherService::CancelRequest(int request_id) {
+  ScopedVector<BitmapFetcherRequest>::iterator iter;
+  for (iter = requests_.begin(); iter != requests_.end(); ++iter) {
+    if ((*iter)->request_id() == request_id) {
+      requests_.erase(iter);
+      // Deliberately leave the associated fetcher running to populate cache.
+      return;
+    }
+  }
+}
+
+BitmapFetcherService::RequestId BitmapFetcherService::RequestImage(
+    const GURL& url,
+    Observer* observer) {
+  // Create a new request, assigning next available request ID.
+  ++current_request_id_;
+  if (current_request_id_ == REQUEST_ID_INVALID)
+    ++current_request_id_;
+  int request_id = current_request_id_;
+  scoped_ptr<BitmapFetcherRequest> request(
+      new BitmapFetcherRequest(request_id, observer));
+
+  // Check for existing images first.
+  base::OwningMRUCache<GURL, CacheEntry*>::iterator iter = cache_.Get(url);
+  if (iter != cache_.end()) {
+    BitmapFetcherService::CacheEntry* entry = iter->second;
+    request->NotifyImageChanged(*(entry->bitmap.get()));
+
+    // There is no request ID associated with this - data is already delivered.
+    return REQUEST_ID_INVALID;
+  }
+
+  // Limit number of simultaneous in-flight requests.
+  if (requests_.size() > kMaxRequests)
+    return REQUEST_ID_INVALID;
+
+  // Make sure there's a fetcher for this URL and attach to request.
+  const chrome::BitmapFetcher* fetcher = EnsureFetcherForUrl(url);
+  request->set_fetcher(fetcher);
+
+  requests_.push_back(request.release());
+  return requests_.back()->request_id();
+}
+
+void BitmapFetcherService::Prefetch(const GURL& url) {
+  EnsureFetcherForUrl(url);
+}
+
+chrome::BitmapFetcher* BitmapFetcherService::CreateFetcher(const GURL& url) {
+  chrome::BitmapFetcher* new_fetcher = new chrome::BitmapFetcher(url, this);
+
+  new_fetcher->Start(
+      context_->GetRequestContext(),
+      std::string(),
+      net::URLRequest::CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE,
+      net::LOAD_NORMAL);
+  return new_fetcher;
+}
+
+const chrome::BitmapFetcher* BitmapFetcherService::EnsureFetcherForUrl(
+    const GURL& url) {
+  const chrome::BitmapFetcher* fetcher = FindFetcherForUrl(url);
+  if (fetcher)
+    return fetcher;
+
+  chrome::BitmapFetcher* new_fetcher = CreateFetcher(url);
+  active_fetchers_.push_back(new_fetcher);
+  return new_fetcher;
+}
+
+const chrome::BitmapFetcher* BitmapFetcherService::FindFetcherForUrl(
+    const GURL& url) {
+  for (BitmapFetchers::iterator iter = active_fetchers_.begin();
+       iter != active_fetchers_.end();
+       ++iter) {
+    if (url == (*iter)->url())
+      return *iter;
+  }
+  return NULL;
+}
+
+void BitmapFetcherService::RemoveFetcher(const chrome::BitmapFetcher* fetcher) {
+  for (BitmapFetchers::iterator iter = active_fetchers_.begin();
+       iter != active_fetchers_.end();
+       ++iter) {
+    if (fetcher == (*iter)) {
+      active_fetchers_.erase(iter);
+      return;
+    }
+  }
+  NOTREACHED();  // RemoveFetcher should always result in removal.
+}
+
+void BitmapFetcherService::OnFetchComplete(const GURL url,
+                                           const SkBitmap* bitmap) {
+  DCHECK(bitmap);  // can never be NULL, guaranteed by BitmapFetcher.
+
+  const chrome::BitmapFetcher* fetcher = FindFetcherForUrl(url);
+  DCHECK(fetcher);
+
+  // Notify all attached requests of completion.
+  ScopedVector<BitmapFetcherRequest>::iterator iter = requests_.begin();
+  while (iter != requests_.end()) {
+    if ((*iter)->get_fetcher() == fetcher) {
+      (*iter)->NotifyImageChanged(*bitmap);
+      iter = requests_.erase(iter);
+    } else {
+      ++iter;
+    }
+  }
+
+  if (!bitmap->isNull()) {
+    CacheEntry* entry = new CacheEntry;
+    entry->bitmap.reset(new SkBitmap(*bitmap));
+    cache_.Put(fetcher->url(), entry);
+  }
+
+  RemoveFetcher(fetcher);
+}