Implement prefetching in chrome

With this CL (see also issue 2910009), chrome will support basic
prefetching.  You can optionally deactivate prefetching with the
command line argument --disable-prefetch.

A new RequestPriority was created as well, IDLE, which is lower
than LOWEST.  Unfortunately, SPDY has only two bits for priority, so
as a temporary measure (pending SPDY v3 which will have three), we
have a mapping in SPDY that folds net::LOWEST and net::IDLE together.

BUG=13505
TEST=http://gemal.dk/browserspy/prefetch.php

Review URL: http://codereview.chromium.org/3050016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@54421 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 111 insertions, 25 deletions

diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 8d5fe26..43889ac 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -560,7 +560,8 @@ class HostResolverImpl::IPv6ProbeJob
 // and increasing for lower priorities.
 COMPILE_ASSERT(HIGHEST == 0u &&
                LOWEST > HIGHEST &&
-               NUM_PRIORITIES > LOWEST,
+               IDLE > LOWEST &&
+               NUM_PRIORITIES > IDLE,
                priority_indexes_incompatible);
 
 // JobPool contains all the information relating to queued requests, including
diff --git a/net/base/request_priority.h b/net/base/request_priority.h
index 6d9b2a5..ca7a1ec 100644
--- a/net/base/request_priority.h
+++ b/net/base/request_priority.h
@@ -15,10 +15,10 @@ enum RequestPriority {
   MEDIUM,
   LOW,
   LOWEST,
+  IDLE,
   NUM_PRIORITIES,
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_REQUEST_PRIORITY_H__
-
diff --git a/net/http/http_network_transaction.cc b/net/http/http_network_transaction.cc
index e553ec4..ee98cca 100644
--- a/net/http/http_network_transaction.cc
+++ b/net/http/http_network_transaction.cc
@@ -1882,6 +1882,22 @@ std::string HttpNetworkTransaction::DescribeState(State state) {
   return description;
 }
 
+// TODO(gavinp): re-adjust this once SPDY v3 has three priority bits,
+// eliminating the need for this folding.
+int ConvertRequestPriorityToSpdyPriority(const RequestPriority priority) {
+  DCHECK(HIGHEST <= priority && priority < NUM_PRIORITIES);
+  switch (priority) {
+    case LOWEST:
+      return SPDY_PRIORITY_LOWEST-1;
+    case IDLE:
+      return SPDY_PRIORITY_LOWEST;
+    default:
+      return priority;
+  }
+}
+
+
+
 #undef STATE_CASE
 
 }  // namespace net
diff --git a/net/http/http_network_transaction.h b/net/http/http_network_transaction.h
index 695d7b9..b3a083c 100644
--- a/net/http/http_network_transaction.h
+++ b/net/http/http_network_transaction.h
@@ -340,6 +340,8 @@ class HttpNetworkTransaction : public HttpTransaction {
   DISALLOW_COPY_AND_ASSIGN(HttpNetworkTransaction);
 };
 
+int ConvertRequestPriorityToSpdyPriority(RequestPriority priority);
+
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_TRANSACTION_H_
diff --git a/net/socket/client_socket_pool_base_unittest.cc b/net/socket/client_socket_pool_base_unittest.cc
index 55f1949..bc3669d 100644
--- a/net/socket/client_socket_pool_base_unittest.cc
+++ b/net/socket/client_socket_pool_base_unittest.cc
@@ -749,7 +749,7 @@ TEST_F(ClientSocketPoolBaseTest, TotalLimitRespectsPriority) {
   EXPECT_EQ(5, GetOrderOfRequest(7));
 
   // Make sure we test order of all requests made.
-  EXPECT_EQ(kIndexOutOfBounds, GetOrderOfRequest(8));
+  EXPECT_EQ(kIndexOutOfBounds, GetOrderOfRequest(9));
 }
 
 TEST_F(ClientSocketPoolBaseTest, TotalLimitRespectsGroupLimit) {
@@ -1026,6 +1026,7 @@ TEST_F(ClientSocketPoolBaseTest, PendingRequests) {
 
   EXPECT_EQ(OK, StartRequest("a", kDefaultPriority));
   EXPECT_EQ(OK, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", IDLE));
   EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", LOWEST));
   EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", MEDIUM));
   EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", HIGHEST));
@@ -1040,14 +1041,15 @@ TEST_F(ClientSocketPoolBaseTest, PendingRequests) {
 
   EXPECT_EQ(1, GetOrderOfRequest(1));
   EXPECT_EQ(2, GetOrderOfRequest(2));
-  EXPECT_EQ(6, GetOrderOfRequest(3));
-  EXPECT_EQ(4, GetOrderOfRequest(4));
-  EXPECT_EQ(3, GetOrderOfRequest(5));
-  EXPECT_EQ(5, GetOrderOfRequest(6));
-  EXPECT_EQ(7, GetOrderOfRequest(7));
+  EXPECT_EQ(8, GetOrderOfRequest(3));
+  EXPECT_EQ(6, GetOrderOfRequest(4));
+  EXPECT_EQ(4, GetOrderOfRequest(5));
+  EXPECT_EQ(3, GetOrderOfRequest(6));
+  EXPECT_EQ(5, GetOrderOfRequest(7));
+  EXPECT_EQ(7, GetOrderOfRequest(8));
 
   // Make sure we test order of all requests made.
-  EXPECT_EQ(kIndexOutOfBounds, GetOrderOfRequest(8));
+  EXPECT_EQ(kIndexOutOfBounds, GetOrderOfRequest(9));
 }
 
 TEST_F(ClientSocketPoolBaseTest, PendingRequests_NoKeepAlive) {
diff --git a/net/spdy/spdy_network_transaction_unittest.cc b/net/spdy/spdy_network_transaction_unittest.cc
index 66feee0..f29d69f 100644
--- a/net/spdy/spdy_network_transaction_unittest.cc
+++ b/net/spdy/spdy_network_transaction_unittest.cc
@@ -289,6 +289,59 @@ TEST_P(SpdyNetworkTransactionTest, Get) {
   EXPECT_EQ("hello!", out.response_data);
 }
 
+TEST_P(SpdyNetworkTransactionTest, GetAtEachPriority) {
+  for (RequestPriority p = HIGHEST; p < NUM_PRIORITIES;
+       p = RequestPriority(p+1)) {
+    // Construct the request.
+    scoped_ptr<spdy::SpdyFrame> req(ConstructSpdyGet(NULL, 0, false, 1, p));
+    MockWrite writes[] = { CreateMockWrite(*req) };
+
+    const int spdy_prio = reinterpret_cast<spdy::SpdySynStreamControlFrame*>(
+        req.get())->priority();
+    // this repeats the RequestPriority-->SpdyPriority mapping from
+    // SpdyFramer::ConvertRequestPriorityToSpdyPriority to make
+    // sure it's being done right.
+    switch(p) {
+      case HIGHEST:
+        EXPECT_EQ(0, spdy_prio);
+        break;
+      case MEDIUM:
+        EXPECT_EQ(1, spdy_prio);
+        break;
+      case LOW:
+      case LOWEST:
+        EXPECT_EQ(2, spdy_prio);
+        break;
+      case IDLE:
+        EXPECT_EQ(3, spdy_prio);
+        break;
+      default:
+        FAIL();
+    }
+
+    scoped_ptr<spdy::SpdyFrame> resp(ConstructSpdyGetSynReply(NULL, 0, 1));
+    scoped_ptr<spdy::SpdyFrame> body(ConstructSpdyBodyFrame(1, true));
+    MockRead reads[] = {
+      CreateMockRead(*resp),
+      CreateMockRead(*body),
+      MockRead(true, 0, 0)  // EOF
+    };
+
+    scoped_refptr<DelayedSocketData> data(
+        new DelayedSocketData(1, reads, arraysize(reads),
+                              writes, arraysize(writes)));
+    HttpRequestInfo http_req = CreateGetRequest();
+    http_req.priority = p;
+
+    NormalSpdyTransactionHelper helper(http_req, BoundNetLog(), GetParam());
+    helper.RunToCompletion(data.get());
+    TransactionHelperResult out = helper.output();
+    EXPECT_EQ(OK, out.rv);
+    EXPECT_EQ("HTTP/1.1 200 OK", out.status_line);
+    EXPECT_EQ("hello!", out.response_data);
+  }
+}
+
 // Start three gets simultaniously; making sure that multiplexed
 // streams work properly.
 
@@ -1482,7 +1535,8 @@ TEST_P(SpdyNetworkTransactionTest, SynReplyHeadersVary) {
     spdy::SYN_REPLY,                              // Syn Reply
     1,                                            // Stream ID
     0,                                            // Associated Stream ID
-    SPDY_PRIORITY_LOWEST,                         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                                  // Priority
     spdy::CONTROL_FLAG_NONE,                      // Control Flags
     false,                                        // Compressed
     spdy::INVALID,                                // Status
@@ -1650,7 +1704,8 @@ TEST_P(SpdyNetworkTransactionTest, InvalidSynReply) {
     spdy::SYN_REPLY,              // Kind = SynReply
     1,                            // Stream ID
     0,                            // Associated stream ID
-    SPDY_PRIORITY_LOWEST,         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                  // Priority
     spdy::CONTROL_FLAG_NONE,      // Control Flags
     false,                        // Compressed
     spdy::INVALID,                // Status
@@ -2411,7 +2466,8 @@ TEST_P(SpdyNetworkTransactionTest, SettingsSaved) {
     spdy::SYN_REPLY,                              // Syn Reply
     1,                                            // Stream ID
     0,                                            // Associated Stream ID
-    SPDY_PRIORITY_LOWEST,                         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                                  // Priority
     spdy::CONTROL_FLAG_NONE,                      // Control Flags
     false,                                        // Compressed
     spdy::INVALID,                                // Status
@@ -2515,7 +2571,8 @@ TEST_P(SpdyNetworkTransactionTest, SettingsPlayback) {
     spdy::SYN_REPLY,                              // Syn Reply
     1,                                            // Stream ID
     0,                                            // Associated Stream ID
-    SPDY_PRIORITY_LOWEST,                         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                                  // Priority
     spdy::CONTROL_FLAG_NONE,                      // Control Flags
     false,                                        // Compressed
     spdy::INVALID,                                // Status
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index 9f2b82f..7ff500a 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -226,7 +226,7 @@ net::Error SpdySession::Connect(
     const std::string& group_name,
     const scoped_refptr<TCPSocketParams>& destination,
     RequestPriority priority) {
-  DCHECK(priority >= SPDY_PRIORITY_HIGHEST && priority <= SPDY_PRIORITY_LOWEST);
+  DCHECK(priority >= net::HIGHEST && priority < net::NUM_PRIORITIES);
 
   // If the connect process is started, let the caller continue.
   if (state_ > IDLE)
@@ -385,8 +385,7 @@ int SpdySession::CreateStreamImpl(
 
   LOG(INFO) << "SpdyStream: Creating stream " << stream_id << " for " << url;
   // TODO(mbelshe): Optimize memory allocations
-  DCHECK(priority >= SPDY_PRIORITY_HIGHEST &&
-         priority <= SPDY_PRIORITY_LOWEST);
+  DCHECK(priority >= net::HIGHEST && priority < net::NUM_PRIORITIES);
 
   DCHECK_EQ(active_streams_[stream_id].get(), stream.get());
   return OK;
@@ -404,8 +403,10 @@ int SpdySession::WriteSynStream(
   CHECK_EQ(stream->stream_id(), stream_id);
 
   scoped_ptr<spdy::SpdySynStreamControlFrame> syn_frame(
-      spdy_framer_.CreateSynStream(stream_id, 0, priority, flags, false,
-                                   headers.get()));
+      spdy_framer_.CreateSynStream(
+          stream_id, 0,
+          ConvertRequestPriorityToSpdyPriority(priority),
+          flags, false, headers.get()));
   QueueFrame(syn_frame.get(), priority, stream);
 
   static StatsCounter spdy_requests("spdy.requests");
diff --git a/net/spdy/spdy_stream_unittest.cc b/net/spdy/spdy_stream_unittest.cc
index 4daad96..471a1786 100644
--- a/net/spdy/spdy_stream_unittest.cc
+++ b/net/spdy/spdy_stream_unittest.cc
@@ -141,7 +141,7 @@ TEST_F(SpdyStreamTest, SendDataAfterOpen) {
     spdy::SYN_STREAM,
     1,
     0,
-    SPDY_PRIORITY_LOWEST,
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
     spdy::CONTROL_FLAG_NONE,
     false,
     spdy::INVALID,
diff --git a/net/spdy/spdy_test_util.cc b/net/spdy/spdy_test_util.cc
index 5d65b4a..2b75b0c 100644
--- a/net/spdy/spdy_test_util.cc
+++ b/net/spdy/spdy_test_util.cc
@@ -8,6 +8,8 @@
 
 #include "base/basictypes.h"
 #include "base/string_util.h"
+#include "net/http/http_network_transaction.h"
+#include "net/spdy/spdy_framer.h"
 
 namespace net {
 
@@ -261,7 +263,8 @@ spdy::SpdyFrame* ConstructSpdyGet(const char* const url,
     spdy::SYN_STREAM,             // Kind = Syn
     stream_id,                    // Stream ID
     0,                            // Associated stream ID
-    request_priority,             // Priority
+    net::ConvertRequestPriorityToSpdyPriority(request_priority),
+                                  // Priority
     spdy::CONTROL_FLAG_FIN,       // Control Flags
     compressed,                   // Compressed
     spdy::INVALID,                // Status
@@ -319,7 +322,8 @@ spdy::SpdyFrame* ConstructSpdyGet(const char* const extra_headers[],
     spdy::SYN_STREAM,             // Kind = Syn
     stream_id,                    // Stream ID
     0,                            // Associated stream ID
-    request_priority,             // Priority
+    net::ConvertRequestPriorityToSpdyPriority(request_priority),
+                                  // Priority
     spdy::CONTROL_FLAG_FIN,       // Control Flags
     compressed,                   // Compressed
     spdy::INVALID,                // Status
@@ -358,7 +362,8 @@ spdy::SpdyFrame* ConstructSpdyGetSynReply(const char* const extra_headers[],
     spdy::SYN_REPLY,              // Kind = SynReply
     stream_id,                    // Stream ID
     0,                            // Associated stream ID
-    SPDY_PRIORITY_LOWEST,         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                  // Priority
     spdy::CONTROL_FLAG_NONE,      // Control Flags
     false,                        // Compressed
     spdy::INVALID,                // Status
@@ -396,7 +401,8 @@ spdy::SpdyFrame* ConstructSpdyPost(int64 content_length,
     spdy::SYN_STREAM,             // Kind = Syn
     1,                            // Stream ID
     0,                            // Associated stream ID
-    SPDY_PRIORITY_LOWEST,         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                  // Priority
     spdy::CONTROL_FLAG_NONE,      // Control Flags
     false,                        // Compressed
     spdy::INVALID,                // Status
@@ -437,7 +443,8 @@ spdy::SpdyFrame* ConstructSpdyPostSynReply(const char* const extra_headers[],
     spdy::SYN_REPLY,              // Kind = SynReply
     1,                            // Stream ID
     0,                            // Associated stream ID
-    SPDY_PRIORITY_LOWEST,         // Priority
+    net::ConvertRequestPriorityToSpdyPriority(LOWEST),
+                                  // Priority
     spdy::CONTROL_FLAG_NONE,      // Control Flags
     false,                        // Compressed
     spdy::INVALID,                // Status
diff --git a/net/url_request/url_request.h b/net/url_request/url_request.h
index a6ef386..06b1048 100644
--- a/net/url_request/url_request.h
+++ b/net/url_request/url_request.h
@@ -545,7 +545,7 @@ class URLRequest : public NonThreadSafe {
   net::RequestPriority priority() const { return priority_; }
   void set_priority(net::RequestPriority priority) {
     DCHECK_GE(priority, net::HIGHEST);
-    DCHECK_LE(priority, net::LOWEST);
+    DCHECK_LT(priority, net::NUM_PRIORITIES);
     priority_ = priority;
   }