protobuf-c-iter-unpack - fast unpacker for protobuf-c.

Focused on unpacking messages in the same pre-allocated buffer.

• Uses protobuf-c structures
• Generates simple for read and use source code
• Supports all field types
• Does not check the required fields during the parse (as protobuf-c)
• Supports packed repeated data (as protobuf-c)
• Supports merge sub-messages (protobuf-c not support)
• Written for protobuf-c 0.15

You must have installed google protobuf library (and python binding)

Generate source and headers:

# create test.pb-c.h and test.pb-c.c
protoc-c --c_out=. test.proto
# create test_pb2.py for protobuf-c-iter-unpack
protoc --python_out=. test.proto
# create test.pb-iter.h and test.pb-iter.c
protobuf-c-iter-unpack.py test_pb2.py
# test_pb2.py no longer needed
rm test_pb2.py

Example:

// pre-allocate buffer
uint8_t iter_msg_buffer[65535];
size_t iter_msg_buffer_size = sizeof(iter_msg_buffer);

TestMessage* msg = (TestMessage*)iter_msg_buffer;

int ret = test_message__iter_unpack(input_buffer, input_buffer_length, iter_msg_buffer, iter_msg_buffer_size);

if (ret == -2) {
  printf("iter_msg_buffer to small for unpack\n");
} else if (ret == -1) {
  printf("can't unpack message from input_buffer\n");
} else if (ret < 0) {
  printf("unknown error: %d\n", ret);
} else {
  printf("message unpacked sucessful. used %d bytes of iter_msg_buffer\n", ret);
  // handle message
  // ...
}

Tested on: CentOS 6.3 x86-64, Intel(R) Xeon(R) CPU E5620 @ 2.40GHz

Competitors:

• 1. protobuf-c with default malloc allocator
• 2. protobuf-c with fastest linear allocator, don't execute free_unpacked method.
• 3. original google c++ parser
• 4. protobuf-c-iter-unpack

Test data:

• 1. message with 10 fields of uint32 type
• 2. 10 x fixed32
• 3. 10 x fixed64
• 4. 10 x string
• 5. openx test message

Result in millions of unpacking per second. Higher is better.