Handling race condition for pending_transfers_ and its iterators.

Author: larshg

examples/protonect/include/libfreenect2/usb/transfer_pool.h

@@ -29,6 +29,7 @@
 
 #include <deque>
 #include <libusb.h>
+#include <mutex>
 
 #include <libfreenect2/data_callback.h>
 
@@ -70,6 +71,7 @@ class TransferPool
   libusb_device_handle *device_handle_;
   unsigned char device_endpoint_;
 
+  std::mutex pending_transfers_lock_;
   TransferQueue idle_transfers_, pending_transfers_;
   unsigned char *buffer_;
   size_t buffer_size_;

examples/protonect/src/transfer_pool.cpp

@@ -86,6 +86,7 @@ void TransferPool::submit(size_t num_parallel_transfers)
   {
     std::cerr << "[TransferPool::submit] too few idle transfers!" << std::endl;
   }
+  pending_transfers_lock_.lock();
 
   for(size_t i = 0; i < num_parallel_transfers; ++i)
   {
@@ -105,6 +106,8 @@ void TransferPool::submit(size_t num_parallel_transfers)
       std::cerr << "[TransferPool::submit] failed to submit transfer" << std::endl;
     }
   }
+
+  pending_transfers_lock_.unlock();
 }
 
 void TransferPool::cancel()
@@ -160,6 +163,7 @@ void TransferPool::onTransferCompleteStatic(libusb_transfer* transfer)
 
 void TransferPool::onTransferComplete(libusb_transfer* transfer)
 {
+  pending_transfers_lock_.lock();
   // remove transfer from pending queue - should be fast as it is somewhere at the front
   TransferQueue::iterator it = std::find(pending_transfers_.begin(), pending_transfers_.end(), transfer);
 
@@ -170,6 +174,8 @@ void TransferPool::onTransferComplete(libusb_transfer* transfer)
 
   pending_transfers_.erase(it);
 
+  pending_transfers_lock_.unlock();
+
   // process data
   processTransfer(transfer);