HttpCache::Transaction layer allowing parallel validation

net/http/http_cache_unittest.cc

Index: net/http/http_cache_unittest.cc
diff --git a/net/http/http_cache_unittest.cc b/net/http/http_cache_unittest.cc
index 27222a905449abe15cd263149bb25c373a576a89..872e5cefa913572f707ae2c3a08fa1217e7979da 100644
--- a/net/http/http_cache_unittest.cc
+++ b/net/http/http_cache_unittest.cc
@@ -1375,7 +1375,8 @@ TEST(HttpCache, SimpleGET_ManyReaders) {
   base::RunLoop().RunUntilIdle();
 
   // The first request should be a writer at this point, and the subsequent
-  // requests should be pending.
+  // requests should have passed the validation phase and waiting for the
+  // response to be written to the cache before they can read.
 
   EXPECT_EQ(1, cache.network_layer()->transaction_count());
   EXPECT_EQ(0, cache.disk_cache()->open_count());
@@ -1407,6 +1408,175 @@ TEST(HttpCache, SimpleGET_ManyReaders) {
   }
 }
 
+// Tests parallel validation similar to the above test, except here validation
+// request is sent out to the network and results in 304.
+TEST(HttpCache, SimpleGET_ParallelValidation) {
+  MockHttpCache cache;
+
+  std::vector<MockHttpRequest> request;
+  ScopedMockTransaction transaction(kTypicalGET_Transaction);
+  transaction.response_headers =
+      "Etag: \"foopy\"\n"
+      "Cache-Control: max-age=0\n";
+  MockHttpRequest request0(transaction);
+  request.push_back(request0);
+
+  ScopedMockTransaction transaction1(kTypicalGET_Transaction);
+  transaction1.status = "HTTP/1.1 304 Not Modified";
+  transaction1.load_flags |= LOAD_VALIDATE_CACHE;
+  transaction1.response_headers =
+      "Etag: \"foopy\"\n"
+      "Cache-Control: max-age=3600\n";
+  MockHttpRequest request1(transaction1);
+  request.push_back(request1);
+
+  std::vector<Context*> context_list;
+  const int kNumTransactions = 2;
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    context_list.push_back(new Context());
+    Context* c = context_list[i];
+
+    c->result = cache.CreateTransaction(&c->trans);
+    ASSERT_THAT(c->result, IsOk());
+    EXPECT_EQ(LOAD_STATE_IDLE, c->trans->GetLoadState());
+
+    c->result = c->trans->Start(&request[i], c->callback.callback(),
+                                NetLogWithSource());
+  }
+
+  // All requests are waiting for the active entry.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    EXPECT_EQ(LOAD_STATE_WAITING_FOR_CACHE, c->trans->GetLoadState());
+  }
+
+  // Allow all requests to move from the Create queue to the active entry.
+  base::RunLoop().RunUntilIdle();
+
+  // The first request should be a writer at this point, and the subsequent
+  // requests should have passed the validation phase and waiting for the
+  // response to be written to the cache before they can read.
+
+  EXPECT_EQ(2, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  // All requests depend on the writer, and the writer is between Start and
+  // Read, i.e. idle.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    EXPECT_EQ(LOAD_STATE_IDLE, c->trans->GetLoadState());
+  }
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    if (c->result == ERR_IO_PENDING)
+      c->result = c->callback.WaitForResult();
+    ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
+  }
+
+  // We should not have had to re-open the disk entry
+
+  EXPECT_EQ(2, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    delete c;
+  }
+}
+
+// Tests parallel validation similar to the above test, except here cache write
+// fails and the validated transactions should be restarted.
+TEST(HttpCache, SimpleGET_ParallelValidationFailWrite) {
+  MockHttpCache cache;
+
+  std::vector<MockHttpRequest> request;
+  ScopedMockTransaction transaction(kTypicalGET_Transaction);
+  transaction.response_headers =
+      "Etag: \"foopy\"\n"
+      "Cache-Control: max-age=0\n";
+  MockHttpRequest request0(transaction);
+  request.push_back(request0);
+
+  ScopedMockTransaction transaction1(kTypicalGET_Transaction);
+  transaction1.status = "HTTP/1.1 304 Not Modified";
+  transaction1.load_flags |= LOAD_VALIDATE_CACHE;
+  transaction1.response_headers =
+      "Etag: \"foopy\"\n"
+      "Cache-Control: max-age=3600\n";
+  MockHttpRequest request1(transaction1);
+  request.push_back(request1);
+
+  std::vector<Context*> context_list;
+  const int kNumTransactions = 2;
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    context_list.push_back(new Context());
+    Context* c = context_list[i];
+
+    c->result = cache.CreateTransaction(&c->trans);
+    ASSERT_THAT(c->result, IsOk());
+    EXPECT_EQ(LOAD_STATE_IDLE, c->trans->GetLoadState());
+
+    c->result = c->trans->Start(&request[i], c->callback.callback(),
+                                NetLogWithSource());
+  }
+
+  // All requests are waiting for the active entry.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    EXPECT_EQ(LOAD_STATE_WAITING_FOR_CACHE, c->trans->GetLoadState());
+  }
+
+  // Allow all requests to move from the Create queue to the active entry.
+  base::RunLoop().RunUntilIdle();
+
+  // The first request should be a writer at this point, and the subsequent
+  // requests should have passed the validation phase and waiting for the
+  // response to be written to the cache before they can read.
+
+  EXPECT_EQ(2, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  // All requests depend on the writer, and the writer is between Start and
+  // Read, i.e. idle.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    EXPECT_EQ(LOAD_STATE_IDLE, c->trans->GetLoadState());
+  }
+
+  // Fail the request.
+  cache.disk_cache()->set_soft_failures(true);
+  // We have to open the entry again to propagate the failure flag.
+  disk_cache::Entry* en;
+  cache.OpenBackendEntry(kTypicalGET_Transaction.url, &en);
+  en->Close();
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    if (c->result == ERR_IO_PENDING)
+      c->result = c->callback.WaitForResult();
+    ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
+  }
+
+  // We should not have had to re-open the disk entry
+
+  // Since validated transaction was restarted, there is an additional network
+  // transaction created.
+  EXPECT_EQ(3, cache.network_layer()->transaction_count());
+  EXPECT_EQ(1, cache.disk_cache()->open_count());
+  EXPECT_EQ(2, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    delete c;
+  }
+}
+
 // This is a test for http://code.google.com/p/chromium/issues/detail?id=4769.
 // If cancelling a request is racing with another request for the same resource
 // finishing, we have to make sure that we remove both transactions from the
@@ -1451,11 +1621,12 @@ TEST(HttpCache, SimpleGET_RacingReaders) {
   c->result = c->callback.WaitForResult();
   ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
 
-  // Now we have 2 active readers and two queued transactions.
-
+  // Now all transactions should be waiting for read to be invoked. Two readers
+  // are because of the load flags and remaining two transactions were converted
+  // to readers after skipping validation. Note that the remaining two went on
+  // to process the headers in parallel with readers presnt on the entry.
   EXPECT_EQ(LOAD_STATE_IDLE, context_list[2]->trans->GetLoadState());
-  EXPECT_EQ(LOAD_STATE_WAITING_FOR_CACHE,
-            context_list[3]->trans->GetLoadState());
+  EXPECT_EQ(LOAD_STATE_IDLE, context_list[3]->trans->GetLoadState());
 
   c = context_list[1];
   ASSERT_THAT(c->result, IsError(ERR_IO_PENDING));
@@ -1520,12 +1691,16 @@ TEST(HttpCache, SimpleGET_DoomWithPending) {
                                 NetLogWithSource());
   }
 
+  base::RunLoop().RunUntilIdle();
+
   // The first request should be a writer at this point, and the two subsequent
   // requests should be pending. The last request doomed the first entry.
 
   EXPECT_EQ(2, cache.network_layer()->transaction_count());
 
-  // Cancel the first queued transaction.
+  // Cancel the second transaction. Note that this and the 3rd transactions
+  // would have completed their headers phase and would be waiting in the
+  // done_headers_queue when the 2nd transaction is cancelled.
   context_list[1].reset();
 
   for (int i = 0; i < kNumTransactions; ++i) {
@@ -1567,11 +1742,12 @@ TEST(HttpCache, FastNoStoreGET_DoneWithPending) {
   base::RunLoop().RunUntilIdle();
 
   // The first request should be a writer at this point, and the subsequent
-  // requests should be pending.
+  // requests should have completed validation. Since the validation does not
+  // result in a match, a new entry would be created.
 
-  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(3, cache.network_layer()->transaction_count());
   EXPECT_EQ(0, cache.disk_cache()->open_count());
-  EXPECT_EQ(1, cache.disk_cache()->create_count());
+  EXPECT_EQ(2, cache.disk_cache()->create_count());
 
   // Now, make sure that the second request asks for the entry not to be stored.
   request_handler.set_no_store(true);
@@ -1625,6 +1801,9 @@ TEST(HttpCache, SimpleGET_ManyWriters_CancelFirst) {
     if (c->result == ERR_IO_PENDING)
       c->result = c->callback.WaitForResult();
     // Destroy only the first transaction.
+    // This should lead to all transactions to restart, even those that have
+    // validated themselves and were waiting for the writer transaction to
+    // complete writing to the cache.
     if (i == 0) {
       delete c;
       context_list[i] = NULL;
@@ -1649,6 +1828,137 @@ TEST(HttpCache, SimpleGET_ManyWriters_CancelFirst) {
   }
 }
 
+// Tests that a transaction which is in validated queue can be destroyed without
+// any impact to other transactions.
+TEST(HttpCache, SimpleGET_ManyWriters_CancelValidated) {
+  MockHttpCache cache;
+
+  MockHttpRequest request(kSimpleGET_Transaction);
+
+  std::vector<Context*> context_list;
+  const int kNumTransactions = 2;
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    context_list.push_back(new Context());
+    Context* c = context_list[i];
+
+    c->result = cache.CreateTransaction(&c->trans);
+    ASSERT_THAT(c->result, IsOk());
+
+    c->result =
+        c->trans->Start(&request, c->callback.callback(), NetLogWithSource());
+  }
+
+  // Allow all requests to move from the Create queue to the active entry.
+  base::RunLoop().RunUntilIdle();
+
+  // The first request should be a writer at this point, and the subsequent
+  // requests should be pending.
+
+  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    Context* c = context_list[i];
+    if (i == 0 && c->result == ERR_IO_PENDING)
+      c->result = c->callback.WaitForResult();
+    // Destroy one of the transactions waiting after the validated stage.
+    if (i == 1) {
+      delete c;
+      context_list[i] = NULL;
+    }
+  }
+
+  // Complete the rest of the transactions.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    if (i == 1)
+      continue;
+    Context* c = context_list[i];
+    ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
+  }
+
+  // We should have had to re-open the disk entry.
+
+  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    if (i == 1)
+      continue;
+    Context* c = context_list[i];
+    delete c;
+  }
+}
+
+// Tests that a transaction which is currently validating can be destroyed
+// without any impact to other transactions.
+TEST(HttpCache, SimpleGET_ManyWriters_CancelValidating) {
+  MockHttpCache cache;
+
+  MockHttpRequest request(kSimpleGET_Transaction);
+
+  std::vector<Context*> context_list;
+  const int kNumTransactions = 2;
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    context_list.push_back(new Context());
+    Context* c = context_list[i];
+
+    c->result = cache.CreateTransaction(&c->trans);
+    ASSERT_THAT(c->result, IsOk());
+
+    c->result =
+        c->trans->Start(&request, c->callback.callback(), NetLogWithSource());
+  }
+
+  // Delete the currently validating transaction.
+  Context* c = context_list[1];
+  EXPECT_EQ(ERR_IO_PENDING, c->result);
+  delete c;
+  context_list[1] = nullptr;
+
+  // Allow all requests to move from the Create queue to the active entry.
+  base::RunLoop().RunUntilIdle();
+
+  // The first request should be a writer at this point, and the subsequent
+  // requests should be pending.
+
+  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    if (i == 1)
+      continue;
+    Context* c = context_list[i];
+    if (c->result == ERR_IO_PENDING)
+      c->result = c->callback.WaitForResult();
+  }
+
+  // Complete the rest of the transactions.
+  for (int i = 0; i < kNumTransactions; ++i) {
+    if (i == 1)
+      continue;
+    Context* c = context_list[i];
+    ReadAndVerifyTransaction(c->trans.get(), kSimpleGET_Transaction);
+  }
+
+  // We should have had to re-open the disk entry.
+
+  EXPECT_EQ(1, cache.network_layer()->transaction_count());
+  EXPECT_EQ(0, cache.disk_cache()->open_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
+
+  for (int i = 0; i < kNumTransactions; ++i) {
+    if (i == 1)
+      continue;
+    Context* c = context_list[i];
+    delete c;
+  }
+}
+
 // Tests that we can cancel requests that are queued waiting to open the disk
 // cache entry.
 TEST(HttpCache, SimpleGET_ManyWriters_CancelCreate) {
@@ -2540,6 +2850,8 @@ TEST(HttpCache, ETagGET_ConditionalRequest_304_NoStore) {
 //     be returned.
 // (4) loads |kUrl| from cache only -- expects |cached_response_2| to be
 //     returned.
+// The entry will be created once and will be opened for the 3 subsequent
+// requests.
 static void ConditionalizedRequestUpdatesCacheHelper(
     const Response& net_response_1,
     const Response& net_response_2,
@@ -6115,12 +6427,14 @@ TEST(HttpCache, GET_IncompleteResource_Cancel) {
   EXPECT_EQ(5, c->callback.GetResult(rv));
 
   // Cancel the requests.
+  // Since |pending| is currently vaidating the already written headers
+  // it will be restarted as well.
   delete c;
   delete pending;
 
   EXPECT_EQ(1, cache.network_layer()->transaction_count());
   EXPECT_EQ(1, cache.disk_cache()->open_count());
-  EXPECT_EQ(2, cache.disk_cache()->create_count());
+  EXPECT_EQ(1, cache.disk_cache()->create_count());
 
   base::RunLoop().RunUntilIdle();
   RemoveMockTransaction(&transaction);
@@ -6845,46 +7159,6 @@ TEST(HttpCache, WriteMetadata_Fail) {
   EXPECT_EQ(1, cache.disk_cache()->create_count());
 }
 
-// Tests that if a metadata writer transaction hits cache lock timeout, it will
-// error out.
-TEST(HttpCache, WriteMetadata_CacheLockTimeout) {
-  MockHttpCache cache;
-
-  // Write to the cache
-  HttpResponseInfo response;
-  RunTransactionTestWithResponseInfo(cache.http_cache(), kSimpleGET_Transaction,
-                                     &response);
-  EXPECT_FALSE(response.metadata.get());
-
-  MockHttpRequest request(kSimpleGET_Transaction);
-  Context c1;
-  ASSERT_THAT(cache.CreateTransaction(&c1.trans), IsOk());
-  ASSERT_EQ(ERR_IO_PENDING, c1.trans->Start(&request, c1.callback.callback(),
-                                            NetLogWithSource()));
-
-  cache.SimulateCacheLockTimeout();
-
-  // Write meta data to the same entry.
-  scoped_refptr<IOBufferWithSize> buf(new IOBufferWithSize(50));
-  memset(buf->data(), 0, buf->size());
-  base::strlcpy(buf->data(), "Hi there", buf->size());
-  cache.http_cache()->WriteMetadata(GURL(kSimpleGET_Transaction.url),
-                                    DEFAULT_PRIORITY, response.response_time,
-                                    buf.get(), buf->size());
-
-  // Release the buffer before the operation takes place.
-  buf = NULL;
-
-  // Makes sure we finish pending operations.
-  base::RunLoop().RunUntilIdle();
-
-  RunTransactionTestWithResponseInfo(cache.http_cache(), kSimpleGET_Transaction,
-                                     &response);
-
-  // The writer transaction should fail due to cache lock timeout.
-  ASSERT_FALSE(response.metadata.get());
-}
-
 // Tests that we ignore VARY checks when writing metadata since the request
 // headers for the WriteMetadata transaction are made up.
 TEST(HttpCache, WriteMetadata_IgnoreVary) {