First pass at adding http/backend cache to NetLog

net/http/http_cache.h

Index: net/http/http_cache.h
===================================================================
--- net/http/http_cache.h	(revision 68857)
+++ net/http/http_cache.h	(working copy)
@@ -30,6 +30,7 @@
 #include "net/base/cache_type.h"
 #include "net/base/completion_callback.h"
 #include "net/base/load_states.h"
+#include "net/base/net_log.h"
 #include "net/http/http_transaction_factory.h"
 
 class GURL;
@@ -50,7 +51,6 @@
 struct HttpRequestInfo;
 class HttpResponseInfo;
 class IOBuffer;
-class NetLog;
 class ProxyService;
 class SSLConfigService;
 class ViewCacheHelper;
@@ -87,7 +87,8 @@
     // The implementation must not access the factory object after invoking the
     // |callback| because the object can be deleted from within the callback.
     virtual int CreateBackend(disk_cache::Backend** backend,
-                              CompletionCallback* callback) = 0;
+                              CompletionCallback* callback,
+                              NetLog* net_log) = 0;

[rvargas (doing something else), 2010/12/11 00:29:01]

nit: this should be the first argument.

   };
 
   // A default backend factory for the common use cases.
@@ -105,7 +106,8 @@
 
     // BackendFactory implementation.
     virtual int CreateBackend(disk_cache::Backend** backend,
-                              CompletionCallback* callback);
+                              CompletionCallback* callback,
+                              NetLog* net_log);
 
    private:
     CacheType type_;
@@ -138,7 +140,8 @@
   // by the HttpCache and will be destroyed using |delete| when the HttpCache is
   // destroyed.
   HttpCache(HttpTransactionFactory* network_layer,
-            BackendFactory* backend_factory);
+            BackendFactory* backend_factory,
+            NetLog* net_log);
 
   HttpTransactionFactory* network_layer() { return network_layer_.get(); }
 
@@ -212,8 +215,9 @@
     TransactionList    pending_queue;
     bool               will_process_pending_queue;
     bool               doomed;
+    BoundNetLog        net_log;

[rvargas (doing something else), 2010/12/11 00:29:01]

I'm not convinced that making ActiveEntry a source of log events is actually
something that we want.

I'd say that tracking what happens at the HttpCache::Transaction level + at the
disk cache level should be enough for practical purposes. The ActiveEntry is
intended to be just a simple structure in the middle that simplifies bonding
transactions to cache entries.

I think doing this adds too much noise to the log and the code, for the actual
value that provides.

[mmenke, 2010/12/11 01:51:05]

I wasn't sure if they were worth logging or not.  They seem pretty
uninteresting...Until you end up with cache contention, which, admittedly, isn't
too common, though I could see it being useful in those cases.  It's pretty
clearly useless most cases, however.

I'll go ahead and remove them, though I think I might log an event for the
transaction when it's queued/dequeued (Rather than instantly become an active
reader/writer), just to draw attention to it, in the cases where it actually
happens.

 
-    explicit ActiveEntry(disk_cache::Entry*);
+    explicit ActiveEntry(disk_cache::Entry* entry, NetLog* net_log);
     ~ActiveEntry();
   };
 
@@ -293,6 +297,11 @@
   // one (in this case, the entry is no longer valid).
   int AddTransactionToEntry(ActiveEntry* entry, Transaction* trans);
 
+  // Same as AddTransactionToEntry, except it does create a NetLog event for
+  // queuing the event.  Used by OnProcessPendingQueue to prevent redundant
+  // logging.
+  int AddTransactionToEntryInternal(ActiveEntry* entry, Transaction* trans);
+
   // Called when the transaction has finished working with this entry. |cancel|
   // is true if the operation was cancelled by the caller instead of running
   // to completion.
@@ -342,6 +351,8 @@
 
   // Variables ----------------------------------------------------------------
 
+  NetLog* net_log_;
+
   // Used when lazily constructing the disk_cache_.
   scoped_ptr<BackendFactory> backend_factory_;
   bool building_backend_;