Cache Backend Proxy to intercept all cache events from the IO thread.

net/disk_cache/tracing_cache_backend.cc

Index: net/disk_cache/tracing_cache_backend.cc
diff --git a/net/disk_cache/tracing_cache_backend.cc b/net/disk_cache/tracing_cache_backend.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b10c974b8f1cd4c85785f4e3aa3a16f93e1d4ef9
--- /dev/null
+++ b/net/disk_cache/tracing_cache_backend.cc
@@ -0,0 +1,317 @@
+// Copyright (c) 2013 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.
+
+#include "net/disk_cache/tracing_cache_backend.h"
+
+#include "net/base/net_errors.h"
+
+namespace disk_cache {
+
+// Proxies entry objects created by the real underlying backend. Backend users
+// will only see the proxy entries. It is necessary for recording the backend
+// operations since often non-trivial work is invoked directly on entries.
+class EntryProxy : public Entry, public base::RefCountedThreadSafe<EntryProxy> {
+ public:
+  EntryProxy(Entry *entry, TracingCacheBackend* backend);
+  virtual void Doom() OVERRIDE;
+  virtual void Close() OVERRIDE;
+  virtual std::string GetKey() const OVERRIDE;
+  virtual base::Time GetLastUsed() const OVERRIDE;
+  virtual base::Time GetLastModified() const OVERRIDE;
+  virtual int32 GetDataSize(int index) const OVERRIDE;
+  virtual int ReadData(int index, int offset, IOBuffer* buf, int buf_len,
+                       const CompletionCallback& callback) OVERRIDE;
+  virtual int WriteData(int index, int offset, IOBuffer* buf, int buf_len,
+                        const CompletionCallback& callback,
+                        bool truncate) OVERRIDE;
+  virtual int ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                             const CompletionCallback& callback) OVERRIDE;
+  virtual int WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                              const CompletionCallback& callback) OVERRIDE;
+  virtual int GetAvailableRange(int64 offset, int len, int64* start,
+                                const CompletionCallback& callback) OVERRIDE;
+  virtual bool CouldBeSparse() const OVERRIDE;
+  virtual void CancelSparseIO() OVERRIDE;
+  virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
+
+ private:
+  friend class base::RefCountedThreadSafe<EntryProxy>;
+  typedef TracingCacheBackend::Operation Operation;
+  virtual ~EntryProxy();
+
+  struct RwOpExtra {
+    int index;
+    int offset;
+    int buf_len;
+    bool truncate;
+  };
+
+  void RecordEvent(base::TimeTicks start_time, Operation op, RwOpExtra extra,
+                   int result_to_record);
+  void EntryOpComplete(base::TimeTicks start_time, Operation op,
+                       RwOpExtra extra, const CompletionCallback& cb,
+                       int result);
+  Entry* entry_;
+  base::WeakPtr<TracingCacheBackend> backend_;
+
+  DISALLOW_COPY_AND_ASSIGN(EntryProxy);
+};
+
+EntryProxy::EntryProxy(Entry *entry, TracingCacheBackend* backend)
+  : entry_(entry),
+    backend_(backend->AsWeakPtr()) {
+}
+
+void EntryProxy::Doom() {
+  // TODO(pasko): Record the event.
+  entry_->Doom();
+}
+
+void EntryProxy::Close() {
+  // TODO(pasko): Record the event.
+  entry_->Close();
+  Release();
+}
+
+std::string EntryProxy::GetKey() const {
+  return entry_->GetKey();
+}
+
+base::Time EntryProxy::GetLastUsed() const {
+  return entry_->GetLastUsed();
+}
+
+base::Time EntryProxy::GetLastModified() const {
+  return entry_->GetLastModified();
+}
+
+int32 EntryProxy::GetDataSize(int index) const {
+  return entry_->GetDataSize(index);
+}
+
+int EntryProxy::ReadData(int index, int offset, IOBuffer* buf, int buf_len,
+                         const CompletionCallback& callback) {
+  base::TimeTicks start_time = base::TimeTicks::Now();
+  RwOpExtra extra;
+  extra.index = index;
+  extra.offset = offset;
+  extra.buf_len = buf_len;
+  extra.truncate = false;
+  int rv = entry_->ReadData(
+      index, offset, buf, buf_len,
+      base::Bind(&EntryProxy::EntryOpComplete, this, start_time,
+                 TracingCacheBackend::OP_READ, extra, callback));
+  if (rv != net::ERR_IO_PENDING) {
+    RecordEvent(start_time, TracingCacheBackend::OP_READ, extra, rv);
+  }
+  return rv;
+}
+
+int EntryProxy::WriteData(int index, int offset, IOBuffer* buf, int buf_len,
+                      const CompletionCallback& callback,
+                      bool truncate) {
+  base::TimeTicks start_time = base::TimeTicks::Now();
+  RwOpExtra extra;
+  extra.index = index;
+  extra.offset = offset;
+  extra.buf_len = buf_len;
+  extra.truncate = truncate;
+  int rv = entry_->WriteData(index, offset, buf, buf_len,
+      base::Bind(&EntryProxy::EntryOpComplete, this, start_time,
+                 TracingCacheBackend::OP_WRITE, extra, callback),
+      truncate);
+  if (rv != net::ERR_IO_PENDING) {
+    RecordEvent(start_time, TracingCacheBackend::OP_WRITE, extra, rv);
+  }
+  return rv;
+}
+
+int EntryProxy::ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                           const CompletionCallback& callback) {
+  // TODO(pasko): Record the event.
+  return entry_->ReadSparseData(offset, buf, buf_len, callback);
+}
+
+int EntryProxy::WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                            const CompletionCallback& callback) {
+  // TODO(pasko): Record the event.
+  return entry_->WriteSparseData(offset, buf, buf_len, callback);
+}
+
+int EntryProxy::GetAvailableRange(int64 offset, int len, int64* start,
+                              const CompletionCallback& callback) {
+  return entry_->GetAvailableRange(offset, len, start, callback);
+}
+
+bool EntryProxy::CouldBeSparse() const {
+  return entry_->CouldBeSparse();
+}
+
+void EntryProxy::CancelSparseIO() {
+  return entry_->CancelSparseIO();
+}
+
+int EntryProxy::ReadyForSparseIO(const CompletionCallback& callback) {
+  return entry_->ReadyForSparseIO(callback);
+}
+
+void EntryProxy::RecordEvent(base::TimeTicks start_time, Operation op,
+                             RwOpExtra extra, int result_to_record) {
+  // TODO(pasko): Implement.
+}
+
+void EntryProxy::EntryOpComplete(base::TimeTicks start_time, Operation op,
+                                 RwOpExtra extra, const CompletionCallback& cb,
+                                 int result) {
+  RecordEvent(start_time, op, extra, result);
+  if (!cb.is_null()) {
+    cb.Run(result);
+  }
+}
+
+EntryProxy::~EntryProxy() {
+  if (backend_.get()) {
+    backend_->OnDeleteEntry(entry_);
+  }
+}
+
+TracingCacheBackend::TracingCacheBackend(Backend* backend)
+  : backend_(backend) {
+}
+
+TracingCacheBackend::~TracingCacheBackend() {
+}
+
+net::CacheType TracingCacheBackend::GetCacheType() const {
+  return backend_->GetCacheType();
+}
+
+int32 TracingCacheBackend::GetEntryCount() const {
+  return backend_->GetEntryCount();
+}
+
+void TracingCacheBackend::RecordEvent(base::TimeTicks start_time, Operation op,
+                                      std::string key, Entry* entry, int rv) {
+  // TODO(pasko): Implement.
+}
+
+EntryProxy* TracingCacheBackend::FindOrCreateEntryProxy(Entry* entry) {
+  EntryProxy* entry_proxy;
+  EntryToProxyMap::iterator it = open_entries_.find(entry);
+  if (it != open_entries_.end()) {
+    entry_proxy = it->second;
+    entry_proxy->AddRef();
+    return entry_proxy;
+  }
+  entry_proxy = new EntryProxy(entry, this);
+  entry_proxy->AddRef();
+  open_entries_[entry] = entry_proxy;
+  return entry_proxy;
+}
+
+void TracingCacheBackend::OnDeleteEntry(Entry* entry) {
+  EntryToProxyMap::iterator it = open_entries_.find(entry);
+  if (it != open_entries_.end()) {
+    open_entries_.erase(it);
+  }
+}
+
+void TracingCacheBackend::BackendOpComplete(base::TimeTicks start_time,
+                                            Operation op,
+                                            std::string key,
+                                            Entry** entry,
+                                            const CompletionCallback& callback,
+                                            int result) {
+  RecordEvent(start_time, op, key, *entry, result);
+  if (*entry) {
+    *entry = FindOrCreateEntryProxy(*entry);
+  }
+  if (!callback.is_null()) {
+    callback.Run(result);
+  }
+}
+
+net::CompletionCallback TracingCacheBackend::BindCompletion(
+    Operation op, base::TimeTicks start_time, const std::string& key,
+    Entry **entry, const net::CompletionCallback& cb) {
+  return base::Bind(&TracingCacheBackend::BackendOpComplete,
+                    AsWeakPtr(), start_time, op, key, entry, cb);
+}
+
+int TracingCacheBackend::OpenEntry(const std::string& key, Entry** entry,
+                                   const CompletionCallback& callback) {
+  DCHECK(*entry == NULL);
+  base::TimeTicks start_time = base::TimeTicks::Now();
+  int rv = backend_->OpenEntry(key, entry,
+                               BindCompletion(OP_OPEN, start_time, key, entry,
+                                              callback));
+  if (rv != net::ERR_IO_PENDING) {
+    RecordEvent(start_time, OP_OPEN, key, *entry, rv);
+    if (*entry) {
+      *entry = FindOrCreateEntryProxy(*entry);
+    }
+  }
+  return rv;
+}
+
+int TracingCacheBackend::CreateEntry(const std::string& key, Entry** entry,
+                                     const CompletionCallback& callback) {
+  base::TimeTicks start_time = base::TimeTicks::Now();
+  int rv = backend_->CreateEntry(key, entry,
+                                 BindCompletion(OP_CREATE, start_time, key,
+                                                entry, callback));
+  if (rv != net::ERR_IO_PENDING) {
+    RecordEvent(start_time, OP_CREATE, key, *entry, rv);
+    if (*entry) {
+      *entry = FindOrCreateEntryProxy(*entry);
+    }
+  }
+  return rv;
+}
+
+int TracingCacheBackend::DoomEntry(const std::string& key,
+                                   const CompletionCallback& callback) {
+  base::TimeTicks start_time = base::TimeTicks::Now();
+  int rv = backend_->DoomEntry(key, BindCompletion(OP_DOOM_ENTRY,
+                                                   start_time, key, NULL,
+                                                   callback));
+  if (rv != net::ERR_IO_PENDING) {
+    RecordEvent(start_time, OP_DOOM_ENTRY, key, NULL, rv);
+  }
+  return rv;
+}
+
+int TracingCacheBackend::DoomAllEntries(const CompletionCallback& callback) {
+  return backend_->DoomAllEntries(callback);
+}
+
+int TracingCacheBackend::DoomEntriesBetween(base::Time initial_time,
+                                            base::Time end_time,
+                                            const CompletionCallback& cb) {
+  return backend_->DoomEntriesBetween(initial_time, end_time, cb);
+}
+
+int TracingCacheBackend::DoomEntriesSince(base::Time initial_time,
+                                          const CompletionCallback& callback) {
+  return backend_->DoomEntriesSince(initial_time, callback);
+}
+
+int TracingCacheBackend::OpenNextEntry(void** iter, Entry** next_entry,
+                                       const CompletionCallback& callback) {
+  return backend_->OpenNextEntry(iter, next_entry, callback);
+}
+
+void TracingCacheBackend::EndEnumeration(void** iter) {
+  return backend_->EndEnumeration(iter);
+}
+
+void TracingCacheBackend::GetStats(StatsItems* stats) {
+  return backend_->GetStats(stats);
+}
+
+void TracingCacheBackend::OnExternalCacheHit(const std::string& key) {
+  return backend_->OnExternalCacheHit(key);
+}
+
+}  // namespace disk_cache