Rewrite session cache in OpenSSL ports.

net/ssl/ssl_client_session_cache_openssl.h

+// Copyright 2015 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.
+
+#ifndef NET_SSL_SSL_CLIENT_SESSION_CACHE_OPENSSL_H
+#define NET_SSL_SSL_CLIENT_SESSION_CACHE_OPENSSL_H
+
+#include <openssl/ssl.h>
+
+#include <string>
+
+#include "base/containers/mru_cache.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "net/base/net_export.h"
+
+namespace base {
+class Clock;
+}
+
+namespace net {
+
+class NET_EXPORT SSLClientSessionCacheOpenSSL {
+ public:
+  struct Config {
+    // The maximum number of entries in the cache.
+    size_t max_entries = 1024;
+    // The number of calls to Lookup before a new check for expired sessions.
+    size_t expiration_check_count = 256;
+    // How long each session should last.
+    base::TimeDelta timeout = base::TimeDelta::FromHours(1);
+  };
+
+  explicit SSLClientSessionCacheOpenSSL(const Config& config);
+  ~SSLClientSessionCacheOpenSSL();
+
+  size_t size() const;
+
+  // Returns the session associated with |cache_key| and moves it to the front
+  // of the MRU list. Returns null if there is none. The caller is responsible
+  // for taking a reference to the pointer if the cache is destroyed or a call
+  // to Insert is made.
+  SSL_SESSION* Lookup(const std::string& cache_key);
+
+  // Inserts |session| into the cache at |cache_key|. If there is an existing
+  // one, it is released. Every |expiration_check_count| calls, the cache is
+  // checked for stale entries.
+  void Insert(const std::string& cache_key, SSL_SESSION* session);
+
+  // Removes all entries from the cache.
+  void Flush();
+
+  void SetClockForTesting(scoped_ptr<base::Clock> clock);
+
+ private:
+  struct CacheEntry;
+
+  using CacheEntryMap =
+      base::MRUCacheBase<std::string,
+                         CacheEntry*,
+                         base::MRUCachePointerDeletor<CacheEntry*>,
+                         base::MRUCacheHashMap>;
+
+  // Returns true if |entry| is expired as of |now|.
+  bool IsExpired(CacheEntry* entry, base::Time now);
+
+  // Removes all expired sessions from the cache.
+  void FlushExpiredSessions();
+
+  scoped_ptr<base::Clock> clock_;
+  Config config_;
+  CacheEntryMap cache_;
+  size_t lookups_since_flush_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(SSLClientSessionCacheOpenSSL);
+};
+
+}  // namespace net
+
+#endif  // NET_SSL_SSL_CLIENT_SESSION_CACHE_OPENSSL_H