Packet copies are now shallow copies by default

prrt/CMakeLists.txt

@@ -16,6 +16,8 @@ add_subdirectory(util)
 
 add_executable(sender sender.c)
 add_executable(receiver receiver.c)
+add_executable(refcount refcount.c)
 
 target_link_libraries(sender LINK_PUBLIC PRRT UTIL ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries(receiver LINK_PUBLIC PRRT UTIL ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries(refcount LINK_PUBLIC PRRT UTIL ${CMAKE_THREAD_LIBS_INIT})

prrt/proto/types/packet.c

@@ -92,6 +92,11 @@ int PrrtPacket_print(PrrtPacket *packet_ptr) {
 }
 
 PrrtPacket *PrrtPacket_copy(PrrtPacket *original) {
+    __sync_fetch_and_add(&original->refcount, 1);
+    return original;
+}
+
+PrrtPacket *PrrtPacket_deepcopy(PrrtPacket *original) {
     PrrtPacket *newPacket = calloc(1, sizeof(PrrtPacket));
     check_mem(newPacket);
     void *payload = calloc(1, original->payloadLength);
@@ -105,6 +110,8 @@ PrrtPacket *PrrtPacket_copy(PrrtPacket *original) {
     newPacket->sequenceNumber = original->sequenceNumber;
     newPacket->type_priority = original->type_priority;
 
+    newPacket->refcount = 1;
+
 
     return newPacket;
     error:
@@ -122,6 +129,7 @@ create_header(uint8_t priority, prrtSequenceNumber_t seqno, prrtPacketLength_t s
     packet->index = index;
     packet->sequenceNumber = seqno;
     packet->payloadLength = size;
+    packet->refcount = 1;
 
     return packet;
 
@@ -214,6 +222,10 @@ void *encode_general_header(void *buf_ptr, const PrrtPacket *packet) {
 }
 
 bool PrrtPacket_decode(void *srcBuffer, uint16_t srcBufferSize, PrrtPacket *targetPacket) {
+
+    // targetPacket is uninitialized, so we need to set the reference count
+    targetPacket->refcount = 1;
+
     prrtPacketLength_t payload_len = (prrtPacketLength_t) (srcBufferSize - PRRT_PACKET_ENCODED_GENERAL_HEADER_LENGTH);
     targetPacket->type_priority = *(uint8_t *) srcBuffer;
     srcBuffer += 1;
@@ -295,11 +307,17 @@ void *decode_data_header(void *dstBuffer, const void *srcBuffer) {
 }
 
 int PrrtPacket_destroy(PrrtPacket *packet) {
-    if (packet->payload != NULL) {
-        free(packet->payload);
+
+    prrtRefcount_t refcount = __sync_fetch_and_sub(&packet->refcount, 1);
+    if (refcount > 1) {
+        return 0;
+    } else {
+        if (packet->payload != NULL) {
+            free(packet->payload);
+        }
+        free(packet);
+        return 0;
     }
-    free(packet);
-    return 0;
 }
 
 PrrtPacket *PrrtPacket_create_data_packet(uint8_t priority, const void *payloadPointer,

prrt/proto/types/packet.h

@@ -36,6 +36,8 @@ typedef atomic_uint_fast32_t prrtAtomicDeliveryRate_t;
 typedef uint32_t prrtByteCount_t;
 typedef uint8_t prrtPacketType_t;
 
+typedef uint16_t prrtRefcount_t;
+
 typedef struct prrtIncompleteBlock {
     prrtSequenceNumber_t sequenceNumberBase;
     uint16_t repairCycleIndex;
@@ -58,6 +60,8 @@ typedef struct prrtPacket {
     prrtTimedelta_t rtt;
 
     struct sockaddr_in sender_addr;
+
+    prrtRefcount_t refcount;
 } PrrtPacket;
 #define PRRT_PACKET_GENERAL_HEADER_SIZE 8
 #define PRRT_PACKET_ENCODED_GENERAL_HEADER_LENGTH 4
@@ -124,6 +128,8 @@ int PrrtPacket_print(PrrtPacket *packet_ptr);
 
 PrrtPacket *PrrtPacket_copy(PrrtPacket *original);
 
+PrrtPacket *PrrtPacket_deepcopy(PrrtPacket *original);
+
 PrrtPacket *PrrtPacket_create_data_packet(uint8_t priority, const void *payloadPointer,
                                           prrtPacketLength_t dataLength, prrtSequenceNumber_t sequenceNumber,
                                           prrtTimedelta_t targetDelay);

prrt/refcount.c

+#include "proto/types/packet.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+const int prio = 0;
+const int seqnum = 1337;
+const int timedelta = 0;
+
+int main() {
+    const char* payload = "just some example payload";
+    struct prrtPacket *a = PrrtPacket_create_data_packet(prio, payload, strlen(payload), seqnum, timedelta);
+    printf("refcount(a): %u\n\n", a->refcount);
+    struct prrtPacket *b = PrrtPacket_copy(a);
+    printf("refcount(a): %u\nrefcount(b): %u\n\n", a->refcount, b->refcount);
+    PrrtPacket_destroy(a);
+    printf("refcount(b): %u\n", b->refcount);
+    PrrtPacket_destroy(b);
+}