added decrement and enqueue example

Author: ritvikrao

tests/CMakeLists.txt

@@ -2,6 +2,7 @@ add_subdirectory(broadcast)
 add_subdirectory(group)
 add_subdirectory(within-node-bcast)
 add_subdirectory(conds)
+add_subdirectory(decrement_enqueue)
 add_subdirectory(idle)
 add_subdirectory(kNeighbors)
 add_subdirectory(orig-converse/pingpong)

tests/decrement_enqueue/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_reconverse_executable(decrement_enqueue decrement_enqueue.cpp)
+add_test(NAME decrement_enqueue COMMAND decrement_enqueue +pe 1)

tests/decrement_enqueue/decrement_enqueue.cpp

@@ -0,0 +1,50 @@
+// Simple reconverse test for CmiCreateDecrementToEnqueue / CmiDecrementCounter
+// Intended to run with 1 PE on 1 process.
+
+#include "converse.h"
+#include <string.h>
+
+// Handler invoked when the decrement counter reaches zero. Exits the program.
+void exit_handler(void *msg) {
+  // We don't need the message payload; just exit.
+  CmiPrintf("Exit handler called, exiting...\n");
+  CmiExit(0);
+}
+
+// Start function invoked by ConverseInit.
+void test_start(int argc, char **argv) {
+  CmiPrintf("Starting decrement_enqueue test...\n");
+  // Only PE 0 will create and drive the counter per the test spec.
+  if (CmiMyPe() != 0) return;
+
+  int handler = CmiRegisterHandler((CmiHandler)exit_handler);
+
+  // Create a minimal message consisting only of the message header.
+  int msgSize = (int)sizeof(CmiMessageHeader);
+  void *msg = CmiAlloc(msgSize);
+  memset(msg, 0, msgSize);
+
+  // Set handler, destination and size on the header so CmiDecrementCounter
+  // can inspect them when it enqueues the message.
+  CmiSetHandler(msg, handler);
+  CmiMessageHeader *hdr = (CmiMessageHeader *)msg;
+  hdr->destPE = (CmiUInt4)CmiMyPe();
+  hdr->messageSize = msgSize;
+
+  // Create the decrement-to-enqueue helper with initial count 16.
+  DecrementToEnqueueMsg *dte = CmiCreateDecrementToEnqueue(16u, msg);
+
+  // Decrement 16 times; on the 16th call the message will be sent and the
+  // registered handler will call CmiExit.
+  for (int i = 0; i < 16; ++i) {
+    CmiDecrementCounter(dte);
+  }
+
+  // Return from start; scheduler will run and the exit handler will stop it.
+}
+
+int main(int argc, char **argv) {
+  // Start the Converse runtime with our test_start function.
+  ConverseInit(argc, argv, test_start, 0, 0);
+  return 0;
+}