From ff5f0312deff4e67ad68e541f4d3744ab956c3ae Mon Sep 17 00:00:00 2001
From: Andy Cedilnik <andy.cedilnik@kitware.com>
Date: Fri, 1 Aug 2003 16:48:41 -0400
Subject: ENH: Do better test for pthreads

---
 Modules/CheckForPthreads.c | 30 ++++++++++++++++++++++++++
 Modules/FindThreads.cmake  | 53 ++++++++++++++++++++++++++++++++++------------
 2 files changed, 69 insertions(+), 14 deletions(-)
 create mode 100644 Modules/CheckForPthreads.c

diff --git a/Modules/CheckForPthreads.c b/Modules/CheckForPthreads.c
new file mode 100644
index 0000000..0f57245
--- /dev/null
+++ b/Modules/CheckForPthreads.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <pthread.h>
+#include <unistd.h>
+
+void* runner(void*);
+
+int res = 0;
+int main()
+{
+  pthread_t tid[2];
+  pthread_create(&tid[0], 0, runner, (void*)1);
+  pthread_create(&tid[1], 0, runner, (void*)2);
+  
+  usleep(1); // for strange behavior on single-processor sun
+  pthread_join(tid[0], 0);
+  pthread_join(tid[1], 0);
+  
+  return res;
+}
+
+void* runner(void* args)
+{
+  int cc;
+  for ( cc = 0; cc < 10; cc ++ )
+    {
+    printf("%d CC: %d\n", (int)args, cc);
+    }
+  res ++;
+  return 0;
+}
diff --git a/Modules/FindThreads.cmake b/Modules/FindThreads.cmake
index d5cab19..f3050e8 100644
--- a/Modules/FindThreads.cmake
+++ b/Modules/FindThreads.cmake
@@ -16,20 +16,45 @@ ENDIF(CMAKE_SYSTEM MATCHES IRIX)
 CHECK_INCLUDE_FILE("pthread.h" CMAKE_HAVE_PTHREAD_H)
 IF(CMAKE_HAVE_PTHREAD_H)
   IF(NOT CMAKE_HAVE_SPROC_H)
-    CHECK_LIBRARY_EXISTS(pthreads pthread_create "" CMAKE_HAVE_PTHREADS_CREATE)
-    IF(CMAKE_HAVE_PTHREADS_CREATE)
-      SET(CMAKE_THREAD_LIBS_INIT "-lpthreads")
-    ENDIF(CMAKE_HAVE_PTHREADS_CREATE)
-    CHECK_LIBRARY_EXISTS(pthread pthread_create "" CMAKE_HAVE_PTHREAD_CREATE)
-    IF(CMAKE_HAVE_PTHREAD_CREATE)
-      SET(CMAKE_THREAD_LIBS_INIT "-lpthread")
-    ENDIF(CMAKE_HAVE_PTHREAD_CREATE)
-    IF(CMAKE_SYSTEM MATCHES "SunOS.*")
-      CHECK_LIBRARY_EXISTS(thread thr_create "" CMAKE_HAVE_THR_CREATE)
-      IF(CMAKE_HAVE_THR_CREATE)
-        SET(CMAKE_THREAD_LIBS_INIT "-lthread")
-      ENDIF(CMAKE_HAVE_THR_CREATE)
-    ENDIF(CMAKE_SYSTEM MATCHES "SunOS.*")
+    IF("THREADS_HAVE_PTHREAD_ARG" MATCHES "^THREADS_HAVE_PTHREAD_ARG")
+      MESSAGE(STATUS "Check if compiler accepts -pthread")
+      TRY_RUN(THREADS_PTHREAD_ARG THREADS_HAVE_PTHREAD_ARG
+        ${CMAKE_BINARY_DIR}
+        ${CMAKE_ROOT}/Modules/CheckForPthreads.c
+        CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
+        OUTPUT_VARIABLE OUTPUT)
+      IF(THREADS_HAVE_PTHREAD_ARG)
+        IF(THREADS_PTHREAD_ARG MATCHES "^2$")
+          MESSAGE(STATUS "Check if compiler accepts -pthread - yes")
+        ELSE(THREADS_PTHREAD_ARG MATCHES "^2$")
+          MESSAGE(STATUS "Check if compiler accepts -pthread - no")
+          FILE(APPEND ${CMAKE_BINARY_DIR}/CMakeError.log 
+            "Determining if compiler accepts -pthread returned ${THREADS_PTHREAD_ARG} instead of 2. The compiler had the following output:\n${OUTPUT}\n\n")
+        ENDIF(THREADS_PTHREAD_ARG MATCHES "^2$")
+      ELSE(THREADS_HAVE_PTHREAD_ARG)
+        MESSAGE(STATUS "Check if compiler accepts -pthread - no")
+        FILE(APPEND ${CMAKE_BINARY_DIR}/CMakeError.log 
+          "Determining if compiler accepts -pthread failed with the following output:\n${OUTPUT}\n\n")
+      ENDIF(THREADS_HAVE_PTHREAD_ARG)
+    ENDIF("THREADS_HAVE_PTHREAD_ARG" MATCHES "^THREADS_HAVE_PTHREAD_ARG")
+    IF(THREADS_HAVE_PTHREAD_ARG)
+      SET(CMAKE_THREAD_LIBS_INIT "-pthread")
+    ELSE(THREADS_HAVE_PTHREAD_ARG)
+      CHECK_LIBRARY_EXISTS(pthreads pthread_create "" CMAKE_HAVE_PTHREADS_CREATE)
+      IF(CMAKE_HAVE_PTHREADS_CREATE)
+        SET(CMAKE_THREAD_LIBS_INIT "-lpthreads")
+      ENDIF(CMAKE_HAVE_PTHREADS_CREATE)
+      CHECK_LIBRARY_EXISTS(pthread pthread_create "" CMAKE_HAVE_PTHREAD_CREATE)
+      IF(CMAKE_HAVE_PTHREAD_CREATE)
+        SET(CMAKE_THREAD_LIBS_INIT "-lpthread")
+      ENDIF(CMAKE_HAVE_PTHREAD_CREATE)
+      IF(CMAKE_SYSTEM MATCHES "SunOS.*")
+        CHECK_LIBRARY_EXISTS(thread thr_create "" CMAKE_HAVE_THR_CREATE)
+        IF(CMAKE_HAVE_THR_CREATE)
+          SET(CMAKE_THREAD_LIBS_INIT "-lthread")
+        ENDIF(CMAKE_HAVE_THR_CREATE)
+      ENDIF(CMAKE_SYSTEM MATCHES "SunOS.*")
+    ENDIF(THREADS_HAVE_PTHREAD_ARG)
   ENDIF(NOT CMAKE_HAVE_SPROC_H)
 ENDIF(CMAKE_HAVE_PTHREAD_H)
 
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