Http Cache: Convert data writes from sysnchronous to asynchronous.

BUG=21383
TEST=unit tests

(original review for r25873: http://codereview.chromium.org/201065)
Review URL: http://codereview.chromium.org/313013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29792 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 138 insertions, 43 deletions

diff --git a/net/http/http_cache.cc b/net/http/http_cache.cc
index a2b131f..eee9397 100644
--- a/net/http/http_cache.cc
+++ b/net/http/http_cache.cc
@@ -163,6 +163,9 @@ class HttpCache::Transaction : public HttpTransaction {
             cache_read_callback_(new CancelableCompletionCallback<Transaction>(
                 this, &Transaction::OnCacheReadCompleted))),
         ALLOW_THIS_IN_INITIALIZER_LIST(
+            cache_write_callback_(new CancelableCompletionCallback<Transaction>(
+                this, &Transaction::OnCacheWriteCompleted))),
+        ALLOW_THIS_IN_INITIALIZER_LIST(
             entry_ready_callback_(new CancelableCompletionCallback<Transaction>(
                 this, &Transaction::OnCacheEntryReady))) {
   }
@@ -309,15 +312,18 @@ class HttpCache::Transaction : public HttpTransaction {
 
   // Called to write data to the cache entry.  If the write fails, then the
   // cache entry is destroyed.  Future calls to this function will just do
-  // nothing without side-effect.
-  void WriteToEntry(int index, int offset, IOBuffer* data, int data_len);
+  // nothing without side-effect.  Returns a network error code.
+  int WriteToEntry(int index, int offset, IOBuffer* data, int data_len,
+                   CompletionCallback* callback);
 
   // Called to write response_ to the cache entry. |truncated| indicates if the
   // entry should be marked as incomplete.
   void WriteResponseInfoToEntry(bool truncated);
 
-  // Called to append response data to the cache entry.
-  void AppendResponseDataToEntry(IOBuffer* data, int data_len);
+  // Called to append response data to the cache entry.  Returns a network error
+  // code.
+  int AppendResponseDataToEntry(IOBuffer* data, int data_len,
+                                CompletionCallback* callback);
 
   // Called to truncate response content in the entry.
   void TruncateResponseData();
@@ -343,6 +349,9 @@ class HttpCache::Transaction : public HttpTransaction {
   // working with range requests.
   int DoPartialCacheReadCompleted(int result);
 
+  // Performs the needed work after writing data to the cache.
+  int DoCacheWriteCompleted(int result);
+
   // Called to signal completion of the network transaction's Start method:
   void OnNetworkInfoAvailable(int result);
 
@@ -352,6 +361,9 @@ class HttpCache::Transaction : public HttpTransaction {
   // Called to signal completion of the cache's ReadData method:
   void OnCacheReadCompleted(int result);
 
+  // Called to signal completion of the cache's WriteData method:
+  void OnCacheWriteCompleted(int result);
+
   // Called to signal completion of the cache entry's ReadyForSparseIO method:
   void OnCacheEntryReady(int result);
 
@@ -384,6 +396,8 @@ class HttpCache::Transaction : public HttpTransaction {
   scoped_refptr<CancelableCompletionCallback<Transaction> >
       cache_read_callback_;
   scoped_refptr<CancelableCompletionCallback<Transaction> >
+      cache_write_callback_;
+  scoped_refptr<CancelableCompletionCallback<Transaction> >
       entry_ready_callback_;
 };
 
@@ -408,9 +422,10 @@ HttpCache::Transaction::~Transaction() {
   // If there is an outstanding callback, mark it as cancelled so running it
   // does nothing.
   cache_read_callback_->Cancel();
+  cache_write_callback_->Cancel();
 
-  // We could still have a cache read in progress, so we just null the cache_
-  // pointer to signal that we are dead.  See OnCacheReadCompleted.
+  // We could still have a cache read or write in progress, so we just null the
+  // cache_ pointer to signal that we are dead.  See DoCacheReadCompleted.
   cache_.reset();
 }
 
@@ -1274,7 +1289,7 @@ int HttpCache::Transaction::ReadFromNetwork(IOBuffer* data, int data_len) {
 int HttpCache::Transaction::ReadFromEntry(IOBuffer* data, int data_len) {
   DCHECK(entry_);
   int rv;
-  cache_read_callback_->AddRef();  // Balanced in DoCacheReadCompleted.
+  cache_read_callback_->AddRef();  // Balanced in OnCacheReadCompleted.
   if (partial_.get()) {
     rv = partial_->CacheRead(entry_->disk_entry, data, data_len,
                             cache_read_callback_);
@@ -1284,11 +1299,12 @@ int HttpCache::Transaction::ReadFromEntry(IOBuffer* data, int data_len) {
   }
   read_buf_ = data;
   read_buf_len_ = data_len;
-  if (rv >= 0) {
-    rv = DoCacheReadCompleted(rv);
-  } else if (rv != ERR_IO_PENDING) {
+  if (rv != ERR_IO_PENDING)
     cache_read_callback_->Release();
-  }
+
+  if (rv >= 0)
+    rv = DoCacheReadCompleted(rv);
+
   return rv;
 }
 
@@ -1303,22 +1319,29 @@ int HttpCache::Transaction::ReadResponseInfoFromEntry() {
   return read_ok ? OK : ERR_CACHE_READ_FAILURE;
 }
 
-void HttpCache::Transaction::WriteToEntry(int index, int offset,
-                                          IOBuffer* data, int data_len) {
+int HttpCache::Transaction::WriteToEntry(int index, int offset,
+                                         IOBuffer* data, int data_len,
+                                         CompletionCallback* callback) {
   if (!entry_)
-    return;
+    return data_len;
 
   int rv = 0;
   if (!partial_.get() || !data_len) {
-    rv = entry_->disk_entry->WriteData(index, offset, data, data_len, NULL,
+    rv = entry_->disk_entry->WriteData(index, offset, data, data_len, callback,
                                        true);
   } else {
-    rv = partial_->CacheWrite(entry_->disk_entry, data, data_len, NULL);
+    rv = partial_->CacheWrite(entry_->disk_entry, data, data_len, callback);
   }
-  if (rv != data_len) {
+
+  if (rv != ERR_IO_PENDING && rv != data_len) {
     DLOG(ERROR) << "failed to write response data to cache";
     DoneWritingToEntry(false);
+
+    // We want to ignore errors writing to disk and just keep reading from
+    // the network.
+    rv = data_len;
   }
+  return rv;
 }
 
 void HttpCache::Transaction::WriteResponseInfoToEntry(bool truncated) {
@@ -1356,13 +1379,14 @@ void HttpCache::Transaction::WriteResponseInfoToEntry(bool truncated) {
   }
 }
 
-void HttpCache::Transaction::AppendResponseDataToEntry(IOBuffer* data,
-                                                       int data_len) {
+int HttpCache::Transaction::AppendResponseDataToEntry(
+    IOBuffer* data, int data_len, CompletionCallback* callback) {
   if (!entry_ || !data_len)
-    return;
+    return data_len;
 
   int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
-  WriteToEntry(kResponseContentIndex, current_size, data, data_len);
+  return WriteToEntry(kResponseContentIndex, current_size, data, data_len,
+                      callback);
 }
 
 void HttpCache::Transaction::TruncateResponseData() {
@@ -1370,7 +1394,8 @@ void HttpCache::Transaction::TruncateResponseData() {
     return;
 
   // Truncate the stream.
-  WriteToEntry(kResponseContentIndex, 0, NULL, 0);
+  int rv = WriteToEntry(kResponseContentIndex, 0, NULL, 0, NULL);
+  DCHECK(rv != ERR_IO_PENDING);
 }
 
 void HttpCache::Transaction::DoneWritingToEntry(bool success) {
@@ -1400,15 +1425,13 @@ int HttpCache::Transaction::DoNetworkReadCompleted(int result) {
   if (!cache_)
     return HandleResult(ERR_UNEXPECTED);
 
-  AppendResponseDataToEntry(read_buf_, result);
+  cache_write_callback_->AddRef();  // Balanced in DoCacheWriteCompleted.
 
-  if (partial_.get())
-    return DoPartialNetworkReadCompleted(result);
+  result = AppendResponseDataToEntry(read_buf_, result, cache_write_callback_);
+  if (result == ERR_IO_PENDING)
+    return result;
 
-  if (result == 0)  // End of file.
-    DoneWritingToEntry(true);
-
-  return HandleResult(result);
+  return DoCacheWriteCompleted(result);
 }
 
 int HttpCache::Transaction::DoPartialNetworkReadCompleted(int result) {
@@ -1430,7 +1453,6 @@ int HttpCache::Transaction::DoPartialNetworkReadCompleted(int result) {
 
 int HttpCache::Transaction::DoCacheReadCompleted(int result) {
   DCHECK(cache_);
-  cache_read_callback_->Release();  // Balance the AddRef() from Start().
 
   if (!cache_)
     return HandleResult(ERR_UNEXPECTED);
@@ -1465,6 +1487,25 @@ int HttpCache::Transaction::DoPartialCacheReadCompleted(int result) {
   return HandleResult(result);
 }
 
+int HttpCache::Transaction::DoCacheWriteCompleted(int result) {
+  DCHECK(cache_);
+  // Balance the AddRef from DoNetworkReadCompleted.
+  cache_write_callback_->Release();
+  if (!cache_)
+    return HandleResult(ERR_UNEXPECTED);
+
+  if (result < 0)
+    return HandleResult(result);
+
+  if (partial_.get())
+    return DoPartialNetworkReadCompleted(result);
+
+  if (result == 0)  // End of file.
+    DoneWritingToEntry(true);
+
+  return HandleResult(result);
+}
+
 void HttpCache::Transaction::OnNetworkInfoAvailable(int result) {
   DCHECK(result != ERR_IO_PENDING);
 
@@ -1579,9 +1620,14 @@ void HttpCache::Transaction::OnNetworkReadCompleted(int result) {
 }
 
 void HttpCache::Transaction::OnCacheReadCompleted(int result) {
+  cache_read_callback_->Release();  // Balance the AddRef from ReadFromEntry.
   DoCacheReadCompleted(result);
 }
 
+void HttpCache::Transaction::OnCacheWriteCompleted(int result) {
+  DoCacheWriteCompleted(result);
+}
+
 void HttpCache::Transaction::OnCacheEntryReady(int result) {
   DCHECK_EQ(OK, result);
   ValidateEntryHeadersAndContinue(true);
diff --git a/net/http/http_cache_unittest.cc b/net/http/http_cache_unittest.cc
index 9df19c2..371ef2586 100644
--- a/net/http/http_cache_unittest.cc
+++ b/net/http/http_cache_unittest.cc
@@ -128,7 +128,12 @@ class MockDiskEntry : public disk_cache::Entry,
     data_[index].resize(offset + buf_len);
     if (buf_len)
       memcpy(&data_[index][offset], buf->data(), buf_len);
-    return buf_len;
+
+    if (!callback || (test_mode_ & TEST_MODE_SYNC_CACHE_WRITE))
+      return buf_len;
+
+    CallbackLater(callback, buf_len);
+    return net::ERR_IO_PENDING;
   }
 
   virtual int ReadSparseData(int64 offset, net::IOBuffer* buf, int buf_len,
@@ -183,7 +188,11 @@ class MockDiskEntry : public disk_cache::Entry,
       data_[1].resize(real_offset + buf_len);
 
     memcpy(&data_[1][real_offset], buf->data(), buf_len);
-    return buf_len;
+    if (!completion_callback || (test_mode_ & TEST_MODE_SYNC_CACHE_WRITE))
+      return buf_len;
+
+    CallbackLater(completion_callback, buf_len);
+    return net::ERR_IO_PENDING;
   }
 
   virtual int GetAvailableRange(int64 offset, int len, int64* start) {
@@ -691,6 +700,14 @@ struct Response {
   const char* body;
 };
 
+struct Context {
+  Context() : result(net::ERR_IO_PENDING) {}
+
+  int result;
+  TestCompletionCallback callback;
+  scoped_ptr<net::HttpTransaction> trans;
+};
+
 }  // namespace
 
 
@@ -765,6 +782,44 @@ TEST(HttpCache, SimpleGETWithDiskFailures) {
   EXPECT_EQ(2, cache.disk_cache()->create_count());
 }
 
+// Tests that disk failures after the transaction has started don't cause the
+// request to fail.
+TEST(HttpCache, SimpleGETWithDiskFailures2) {
+  MockHttpCache cache;
+
+  MockHttpRequest request(kSimpleGET_Transaction);
+
+  scoped_ptr<Context> c(new Context());
+  int rv = cache.http_cache()->CreateTransaction(&c->trans);
+  EXPECT_EQ(net::OK, rv);
+
+  rv = c->trans->Start(&request, &c->callback, NULL);
+  EXPECT_EQ(net::ERR_IO_PENDING, rv);
+  rv = c->callback.WaitForResult();
+
+  // Start failing request now.
+  cache.disk_cache()->set_soft_failures(true);
+
+  // We have to open the entry again to propagate the failure flag.
+  disk_cache::Entry* en;
+  ASSERT_TRUE(cache.disk_cache()->OpenEntry(kSimpleGET_Transaction.url, &en));
+  en->Close();
+
+  ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
+  c.reset();
+
+  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(1, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  // This one should see an empty cache again.
+  RunTransactionTest(cache.http_cache(), kSimpleGET_Transaction);
+
+  EXPECT_EQ(2, cache.network_layer()->transaction_count());
+  EXPECT_EQ(1, cache.disk_cache()->open_count());
+  EXPECT_EQ(2, cache.disk_cache()->create_count());
+}
+
 TEST(HttpCache, SimpleGET_LoadOnlyFromCache_Hit) {
   MockHttpCache cache;
 
@@ -965,15 +1020,6 @@ TEST(HttpCache, SimpleGET_LoadValidateCache_Implicit) {
   EXPECT_EQ(1, cache.disk_cache()->create_count());
 }
 
-struct Context {
-  int result;
-  TestCompletionCallback callback;
-  scoped_ptr<net::HttpTransaction> trans;
-
-  Context() : result(net::ERR_IO_PENDING) {
-  }
-};
-
 TEST(HttpCache, SimpleGET_ManyReaders) {
   MockHttpCache cache;
 
@@ -2022,7 +2068,8 @@ TEST(HttpCache, UnknownRangeGET_2) {
 
   MockTransaction transaction(kRangeGET_TransactionOK);
   transaction.test_mode = TEST_MODE_SYNC_CACHE_START |
-                          TEST_MODE_SYNC_CACHE_READ;
+                          TEST_MODE_SYNC_CACHE_READ |
+                          TEST_MODE_SYNC_CACHE_WRITE;
   AddMockTransaction(&transaction);
 
   // Write to the cache (70-79).
@@ -2823,7 +2870,8 @@ TEST(HttpCache, SyncRead) {
 
   ScopedMockTransaction transaction(kSimpleGET_Transaction);
   transaction.test_mode |= (TEST_MODE_SYNC_CACHE_START |
-                            TEST_MODE_SYNC_CACHE_READ);
+                            TEST_MODE_SYNC_CACHE_READ |
+                            TEST_MODE_SYNC_CACHE_WRITE);
 
   MockHttpRequest r1(transaction),
                   r2(transaction),
diff --git a/net/http/http_transaction_unittest.h b/net/http/http_transaction_unittest.h
index 4de8efd..2a93237 100644
--- a/net/http/http_transaction_unittest.h
+++ b/net/http/http_transaction_unittest.h
@@ -33,6 +33,7 @@ enum {
   TEST_MODE_SYNC_NET_READ  = 1 << 1,
   TEST_MODE_SYNC_CACHE_START = 1 << 2,
   TEST_MODE_SYNC_CACHE_READ  = 1 << 3,
+  TEST_MODE_SYNC_CACHE_WRITE  = 1 << 4,
 };
 
 typedef void (*MockTransactionHandler)(const net::HttpRequestInfo* request,