Never lock the Pepper proxy lock on the IO thread

ppapi/proxy/udp_socket_filter.h

Index: ppapi/proxy/udp_socket_filter.h
diff --git a/ppapi/proxy/udp_socket_filter.h b/ppapi/proxy/udp_socket_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..5deee105ecfc1e7bfb6aa436d0a2ace4566233cf
--- /dev/null
+++ b/ppapi/proxy/udp_socket_filter.h
@@ -0,0 +1,131 @@
+// 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 PPAPI_PROXY_UDP_SOCKET_FILTER_H_
+#define PPAPI_PROXY_UDP_SOCKET_FILTER_H_
+
+#include <queue>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/memory/ref_counted.h"
+#include "ppapi/c/ppb_udp_socket.h"
+#include "ppapi/c/private/ppb_net_address_private.h"
+#include "ppapi/proxy/plugin_resource.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
+#include "ppapi/proxy/resource_message_filter.h"
+#include "ppapi/shared_impl/tracked_callback.h"
+
+namespace ppapi {
+namespace proxy {
+
+class ResourceMessageReplyParams;
+
+// Handles receiving UDP packets on the IO thread so that when the recipient is
+// not on the main thread, we can post directly to the appropriate thread.
+class PPAPI_PROXY_EXPORT UDPSocketFilter : public ResourceMessageFilter {
+ public:
+  UDPSocketFilter();
+
+  // All these are called on whatever thread the plugin wants, while already
+  // holding the ppapi::ProxyLock. The "slot_available_callback" will be invoked
+  // on the IO thread without the ProxyLock, so that callback is responsible
+  // for posting to another thread and acquiring the ProxyLock if necessary.
+  void AddUDPResource(PP_Instance instance,
+                      PP_Resource resource,
+                      bool private_api,
+                      const base::Closure& slot_available_callback);
+  void RemoveUDPResource(PP_Resource resource);
+  int32_t RequestData(PP_Resource resource,
+                      int32_t num_bytes,
+                      char* buffer,
+                      PP_Resource* addr,
+                      const scoped_refptr<TrackedCallback>& callback);
+
+  // ResourceMessageFilter implementation.
+  bool OnResourceReplyReceived(const ResourceMessageReplyParams& reply_params,
+                               const IPC::Message& nested_msg) override;
+
+  PP_NetAddress_Private GetLastAddrPrivate(PP_Resource resource) const;
+
+  // The maximum number of bytes that each
+  // PpapiPluginMsg_PPBUDPSocket_PushRecvResult message is allowed to carry.
+  static const int32_t kMaxReadSize;
+  // The maximum number that we allow for setting
+  // PP_UDPSOCKET_OPTION_RECV_BUFFER_SIZE. This number is only for input
+  // argument sanity check, it doesn't mean the browser guarantees to support
+  // such a buffer size.
+  static const int32_t kMaxReceiveBufferSize;
+  // The maximum number of received packets that we allow instances of this
+  // class to buffer.
+  static const size_t kPluginReceiveBufferSlots;
+
+ private:
+  // The queue of received data intended for 1 UDPSocketResourceBase. All usage
+  // must be protected by UDPSocketFilter::lock_.
+  class RecvQueue {
+   public:
+    explicit RecvQueue(PP_Instance instance,
+                       bool private_api,
+                       const base::Closure& slot_available_callback);
+    ~RecvQueue();
+
+    // Called on the IO thread when data is received. It will post |callback_|
+    // if it's valid, otherwise push the data on buffers_.
+    // The ppapi::ProxyLock should *not* be held, and won't be acquired.
+    void DataReceivedOnIOThread(int32_t result,
+                                const std::string& d,
+                                const PP_NetAddress_Private& addr);
+    // Called on whatever thread the plugin chooses. Must already hold the
+    // PpapiProxyLock. Returns a code from pp_errors.h, or a positive number.
+    //
+    // Note, the out-params are owned by the plugin, and if the request can't be
+    // handled immediately, they will be written later just before the callback
+    // is invoked.
+    int32_t RequestData(int32_t num_bytes,
+                        char* buffer_out,
+                        PP_Resource* addr_out,
+                        const scoped_refptr<TrackedCallback>& callback);
+    PP_NetAddress_Private GetLastAddrPrivate() const;
+
+   private:
+    struct RecvBuffer {
+      int32_t result;
+      std::string data;
+      PP_NetAddress_Private addr;
+    };
+    std::queue<RecvBuffer> recv_buffers_;
+
+    PP_Instance pp_instance_;
+    scoped_refptr<ppapi::TrackedCallback> recvfrom_callback_;
+    char* read_buffer_;
+    int32_t bytes_to_read_;
+    PP_Resource* recvfrom_addr_resource_;
+    PP_NetAddress_Private last_recvfrom_addr_;
+    bool private_api_;
+    // Callback to invoke when a UDP receive slot is available.
+    base::Closure slot_available_callback_;
+  };
+
+ private:
+  // This is deleted via RefCountedThreadSafe (see ResourceMessageFilter).
+  ~UDPSocketFilter();
+  void OnPluginMsgPushRecvResult(const ResourceMessageReplyParams& params,
+                                 int32_t result,
+                                 const std::string& data,
+                                 const PP_NetAddress_Private& addr);
+
+  // Lock order (if >1 acquired):
+  // 1 ppapi::ProxyLock
+  // 2--> Filter lock
+  mutable base::Lock lock_;

[raymes, 2015/03/10 02:53:15]

Maybe make a note that this protects queues_?

[dmichael (off chromium), 2015/03/23 20:50:06]

Done.

+  base::ScopedPtrHashMap<PP_Resource, RecvQueue> queues_;
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_UDP_SOCKET_FILTER_H_