Improving and adding an in-memory MRU cache to DiskBasedCertCache.

net/http/disk_based_cert_cache.cc

 // Copyright (c) 2014 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/http/disk_based_cert_cache.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 189 matching lines @@
   return OK;
 }
 
 int DiskBasedCertCache::WriteWorker::DoOpen() {
   state_ = STATE_OPEN_COMPLETE;
   return backend_->OpenEntry(key_, &entry_, io_callback_);
 }
 
 int DiskBasedCertCache::WriteWorker::DoOpenComplete(int rv) {
   if (rv < 0) {
-    state_ = STATE_NONE;
     return rv;
   }

[wtc, 2014/07/01 02:11:31]

Nit: omit the curly braces in these simple if statements.

   state_ = STATE_WRITE;
   return OK;
 }
 
 int DiskBasedCertCache::WriteWorker::DoWrite() {
   std::string write_data;
   bool encoded = X509Certificate::GetDEREncoded(cert_handle_, &write_data);
 
   if (!encoded) {
-    state_ = STATE_NONE;
     return ERR_FAILED;
   }
 
   buffer_ = new IOBuffer(write_data.size());
   io_buf_len_ = write_data.size();
   memcpy(buffer_->data(), write_data.data(), io_buf_len_);
 
   state_ = STATE_WRITE_COMPLETE;
 
   return entry_->WriteData(0 /* index */,
                            0 /* offset */,
                            buffer_,
                            write_data.size(),
                            io_callback_,
                            true /* truncate */);
 }
 
 int DiskBasedCertCache::WriteWorker::DoWriteComplete(int rv) {
-  state_ = STATE_NONE;
   if (rv < io_buf_len_)
     return ERR_FAILED;
 
   return OK;
 }
 
 void DiskBasedCertCache::WriteWorker::RunCallbacks(int rv) {
   std::string key;
   if (rv >= 0)
     key = key_;
@@ skipping 28 matching lines @@
 // at the same time; instead, call AddCallback to add a user_callback_ to
 // the the existing ReadWorker.
 class DiskBasedCertCache::ReadWorker {
  public:
   // |backend| is the backend to read |certificate| from, using
   // |key| as the key for the disk_cache::Entry.
   // |cleanup_callback| is called to clean up this ReadWorker,
   // regardless of success or failure.
   ReadWorker(disk_cache::Backend* backend,
              const std::string& key,
-             const base::Closure& cleanup_callback);
+             const GetCallback& cleanup_callback);
 
   ~ReadWorker();
 
   // Reads the given certificate from the cache. On completion, will invoke all
   // user callbacks.
   void Start();
 
   // Adds a callback to the set of callbacks to be run when this
   // ReadWorker finishes processing.
   void AddCallback(const GetCallback& user_callback);
@@ skipping 27 matching lines @@
   X509Certificate::OSCertHandle cert_handle_;
   std::string key_;
   bool canceled_;
 
   disk_cache::Entry* entry_;
 
   State state_;
   scoped_refptr<IOBuffer> buffer_;
   int io_buf_len_;
 
-  base::Closure cleanup_callback_;
+  GetCallback cleanup_callback_;
   std::vector<GetCallback> user_callbacks_;
   CompletionCallback io_callback_;
 };
 
-DiskBasedCertCache::ReadWorker::ReadWorker(
-    disk_cache::Backend* backend,
-    const std::string& key,
-    const base::Closure& cleanup_callback)
+DiskBasedCertCache::ReadWorker::ReadWorker(disk_cache::Backend* backend,
+                                           const std::string& key,
+                                           const GetCallback& cleanup_callback)
     : backend_(backend),
       cert_handle_(NULL),
       key_(key),
       canceled_(false),
       entry_(NULL),
       state_(STATE_NONE),
       io_buf_len_(0),
       cleanup_callback_(cleanup_callback),
       io_callback_(
           base::Bind(&ReadWorker::OnIOComplete, base::Unretained(this))) {
@@ skipping 55 matching lines @@
   return rv;
 }
 
 int DiskBasedCertCache::ReadWorker::DoOpen() {
   state_ = STATE_OPEN_COMPLETE;
   return backend_->OpenEntry(key_, &entry_, io_callback_);
 }
 
 int DiskBasedCertCache::ReadWorker::DoOpenComplete(int rv) {
   if (rv < 0) {
-    state_ = STATE_NONE;
     return rv;
   }
   state_ = STATE_READ;
   return OK;
 }
 
 int DiskBasedCertCache::ReadWorker::DoRead() {
   state_ = STATE_READ_COMPLETE;
   io_buf_len_ = entry_->GetDataSize(0 /* index */);
   buffer_ = new IOBuffer(io_buf_len_);
   return entry_->ReadData(
       0 /* index */, 0 /* offset */, buffer_, io_buf_len_, io_callback_);
 }
 
 int DiskBasedCertCache::ReadWorker::DoReadComplete(int rv) {
-  state_ = STATE_NONE;
   if (rv < io_buf_len_)
     return ERR_FAILED;
 
   cert_handle_ = X509Certificate::CreateOSCertHandleFromBytes(buffer_->data(),
                                                               io_buf_len_);
   if (!cert_handle_)
     return ERR_FAILED;
 
   return OK;
 }
 
 void DiskBasedCertCache::ReadWorker::RunCallbacks() {
   for (std::vector<GetCallback>::const_iterator it = user_callbacks_.begin();
        it != user_callbacks_.end();
        ++it) {
     it->Run(cert_handle_);
   }
   user_callbacks_.clear();
 }
 
 void DiskBasedCertCache::ReadWorker::Finish(int rv) {
-  cleanup_callback_.Run();
+  cleanup_callback_.Run(cert_handle_);
   cleanup_callback_.Reset();
   RunCallbacks();
   delete this;
 }
 
 void DiskBasedCertCache::ReadWorker::Cancel() {
   canceled_ = true;
 }
 
 DiskBasedCertCache::ReadWorker::~ReadWorker() {
   if (entry_)
     entry_->Close();
   if (cert_handle_)
     X509Certificate::FreeOSCertHandle(cert_handle_);
 }
 
 DiskBasedCertCache::DiskBasedCertCache(disk_cache::Backend* backend)
-    : backend_(backend), weak_factory_(this) {
+    : backend_(backend), mru_cert_cache_(30), weak_factory_(this) {

[wtc, 2014/07/01 02:11:31]

Define a constant with the value 30 near the top of this file.

   DCHECK(backend_);
 }
 
 DiskBasedCertCache::~DiskBasedCertCache() {
   for (WriteWorkerMap::iterator it = write_worker_map_.begin();
        it != write_worker_map_.end();
        ++it) {
     it->second->Cancel();
   }
   for (ReadWorkerMap::iterator it = read_worker_map_.begin();
        it != read_worker_map_.end();
        ++it) {
     it->second->Cancel();
   }
 }
 
 void DiskBasedCertCache::Get(const std::string& key, const GetCallback& cb) {
   DCHECK(!key.empty());
 
+  // If the handle is already in the MRU cache, just return that (via callback).
+  // Note, this will also bring the cert_handle to the front
+  // of the regency list in the MRU cache.

[wtc, 2014/07/01 02:11:31]

1. Typo: regency => recency

2. Move some of the words to the previous line.

+  MRUCertCache::iterator mru_it = mru_cert_cache_.Get(key);
+  if (mru_it != mru_cert_cache_.end()) {
+    cb.Run(mru_it->second);
+    return;
+  }
+
   ReadWorkerMap::iterator it = read_worker_map_.find(key);
 
   if (it == read_worker_map_.end()) {
     ReadWorker* worker =
         new ReadWorker(backend_,
                        key,
                        base::Bind(&DiskBasedCertCache::FinishedReadOperation,
                                   weak_factory_.GetWeakPtr(),
                                   key));
     read_worker_map_[key] = worker;
     worker->AddCallback(cb);
     worker->Start();
   } else {
     it->second->AddCallback(cb);
   }
 }
 
 void DiskBasedCertCache::Set(const X509Certificate::OSCertHandle cert_handle,
                              const SetCallback& cb) {
   DCHECK(!cb.is_null());
   DCHECK(cert_handle);
   std::string key = GetCacheKeyToCert(cert_handle);
 
+  // If |cert_handle| already exists in the MRU cache, there is no need to
+  // re-write it to the disk cache. This will also bring |cert_handle|
+  // to the front of the regency list in the MRU cache.

[wtc, 2014/07/01 02:11:31]

Typo: regency => recency

+  if (mru_cert_cache_.Get(key) != mru_cert_cache_.end()) {
+    cb.Run(key);
+    return;
+  }
+
+  mru_cert_cache_.Put(key, X509Certificate::DupOSCertHandle(cert_handle));

[wtc, 2014/07/01 02:11:31]

A comment that explains why it is advantageous and correct to add the cert to
the MRU cache now should be added.

[brandonsalmon, 2014/07/01 18:19:29]

I no longer think this is that advantageous. (There are many write requests
simultaneously, but in those cases the user callback will just be added to the
WriteWorker).

I moved this to the FinishedWriteOperation function. 

   WriteWorkerMap::iterator it = write_worker_map_.find(key);
 
   if (it == write_worker_map_.end()) {
     WriteWorker* worker =
         new WriteWorker(backend_,
                         key,
                         cert_handle,
                         base::Bind(&DiskBasedCertCache::FinishedWriteOperation,
                                    weak_factory_.GetWeakPtr(),
                                    key));
     write_worker_map_[key] = worker;
     worker->AddCallback(cb);
     worker->Start();
   } else {
     it->second->AddCallback(cb);
   }
 }
 
 void DiskBasedCertCache::FinishedWriteOperation(const std::string& key) {
   write_worker_map_.erase(key);
 }
 
-void DiskBasedCertCache::FinishedReadOperation(const std::string& key) {
+void DiskBasedCertCache::FinishedReadOperation(
+    const std::string& key,
+    X509Certificate::OSCertHandle cert_handle) {
+  if (cert_handle)
+    mru_cert_cache_.Put(key, X509Certificate::DupOSCertHandle(cert_handle));
   read_worker_map_.erase(key);
 }
 
 }  // namespace net