First pass at adding http/backend cache to NetLog

net/http/http_cache.h

 // Copyright (c) 2010 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.
 
 // This file declares a HttpTransactionFactory implementation that can be
 // layered on top of another HttpTransactionFactory to add HTTP caching.  The
 // caching logic follows RFC 2616 (any exceptions are called out in the code).
 //
 // The HttpCache takes a disk_cache::Backend as a parameter, and uses that for
 // the cache storage.
@@ skipping 12 matching lines @@
 #include "base/file_path.h"
 #include "base/hash_tables.h"
 #include "base/message_loop_proxy.h"
 #include "base/non_thread_safe.h"
 #include "base/scoped_ptr.h"
 #include "base/task.h"
 #include "base/weak_ptr.h"
 #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;
 
 namespace disk_cache {
 class Backend;
 class Entry;
 }
 
 namespace net {
 
 class DnsCertProvenanceChecker;
 class DnsRRResolver;
 class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpNetworkDelegate;
 class HttpNetworkSession;
 struct HttpRequestInfo;
 class HttpResponseInfo;
 class IOBuffer;
-class NetLog;
 class ProxyService;
 class SSLConfigService;
 class ViewCacheHelper;
 
 class HttpCache : public HttpTransactionFactory,
                   public base::SupportsWeakPtr<HttpCache>,
                   public NonThreadSafe {
  public:
   ~HttpCache();
 
@@ skipping 16 matching lines @@
    public:
     virtual ~BackendFactory() {}
 
     // The actual method to build the backend. Returns a net error code. If
     // ERR_IO_PENDING is returned, the |callback| will be notified when the
     // operation completes, and |backend| must remain valid until the
     // notification arrives.
     // 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.
   class DefaultBackend : public BackendFactory {
    public:
     // |path| is the destination for any files used by the backend, and
     // |cache_thread| is the thread where disk operations should take place. If
     // |max_bytes| is  zero, a default value will be calculated automatically.
     DefaultBackend(CacheType type, const FilePath& path, int max_bytes,
                    base::MessageLoopProxy* thread);
     virtual ~DefaultBackend();
 
     // Returns a factory for an in-memory cache.
     static BackendFactory* InMemory(int max_bytes);
 
     // BackendFactory implementation.
     virtual int CreateBackend(disk_cache::Backend** backend,
-                              CompletionCallback* callback);
+                              CompletionCallback* callback,
+                              NetLog* net_log);
 
    private:
     CacheType type_;
     const FilePath path_;
     int max_bytes_;
     scoped_refptr<base::MessageLoopProxy> thread_;
   };
 
   // The disk cache is initialized lazily (by CreateTransaction) in this case.
   // The HttpCache takes ownership of the |backend_factory|.
@@ skipping 12 matching lines @@
   // network layer with a shared HttpNetworkSession in order for multiple
   // network layers to share information (e.g. authenication data). The
   // HttpCache takes ownership of the |backend_factory|.
   HttpCache(HttpNetworkSession* session, BackendFactory* backend_factory);
 
   // Initialize the cache from its component parts, which is useful for
   // testing.  The lifetime of the network_layer and backend_factory are managed
   // 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(); }
 
   // Retrieves the cache backend for this HttpCache instance. If the backend
   // is not initialized yet, this method will initialize it. The return value is
   // a network error code, and it could be ERR_IO_PENDING, in which case the
   // |callback| will be notified when the operation completes. The pointer that
   // receives the |backend| must remain valid until the operation completes.
   int GetBackend(disk_cache::Backend** backend, CompletionCallback* callback);
 
@@ skipping 53 matching lines @@
   typedef std::list<Transaction*> TransactionList;
   typedef std::list<WorkItem*> WorkItemList;
 
   struct ActiveEntry {
     disk_cache::Entry* disk_entry;
     Transaction*       writer;
     TransactionList    readers;
     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();
   };
 
   typedef base::hash_map<std::string, ActiveEntry*> ActiveEntriesMap;
   typedef base::hash_map<std::string, PendingOp*> PendingOpsMap;
   typedef std::set<ActiveEntry*> ActiveEntriesSet;
 
   // Methods ------------------------------------------------------------------
 
   // Creates the |backend| object and notifies the |callback| when the operation
@@ skipping 59 matching lines @@
   // Destroys an ActiveEntry (active or doomed).
   void DestroyEntry(ActiveEntry* entry);
 
   // Adds a transaction to an ActiveEntry. If this method returns ERR_IO_PENDING
   // the transaction will be notified about completion via its IO callback. This
   // method returns ERR_CACHE_RACE to signal the transaction that it cannot be
   // added to the provided entry, and it should retry the process with another
   // 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.
   void DoneWithEntry(ActiveEntry* entry, Transaction* trans, bool cancel);
 
   // Called when the transaction has finished writting to this entry. |success|
   // is false if the cache entry should be deleted.
   void DoneWritingToEntry(ActiveEntry* entry, bool success);
 
   // Called when the transaction has finished reading from this entry.
@@ skipping 29 matching lines @@
 
   // Processes BackendCallback notifications.
   void OnIOComplete(int result, PendingOp* entry);
 
   // Processes the backend creation notification.
   void OnBackendCreated(int result, PendingOp* pending_op);
 
 
   // Variables ----------------------------------------------------------------
 
+  NetLog* net_log_;
+
   // Used when lazily constructing the disk_cache_.
   scoped_ptr<BackendFactory> backend_factory_;
   bool building_backend_;
 
   Mode mode_;
 
   scoped_ptr<SSLHostInfoFactoryAdaptor> ssl_host_info_factory_;
 
   scoped_ptr<HttpTransactionFactory> network_layer_;
   scoped_ptr<disk_cache::Backend> disk_cache_;
@@ skipping 11 matching lines @@
 
   typedef base::hash_map<std::string, int> PlaybackCacheMap;
   scoped_ptr<PlaybackCacheMap> playback_cache_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpCache);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_H_