Merge pull request #42 from colesbury/dlopen

Load thread's start routine from separate shared library

7 files changed, 105 insertions, 59 deletions

diff --git a/.gitignore b/.gitignore
index b08795f..7d07faa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,5 @@ install_manifest.txt
 # Build output
 libthreads.a
 libthreads.so
+libthreadsmain.dylib
+libthreadsmain.so
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d6b2fcf..a583a6f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,9 +20,15 @@ set(luasrc
 )
 
 add_torch_package(threads "${src}" "${luasrc}" "Threads")
-
 target_link_libraries(threads luaT TH)
 
+ADD_LIBRARY(threadsmain MODULE lib/thread-main.c)
+IF(APPLE)
+  SET_TARGET_PROPERTIES(threadsmain PROPERTIES
+    LINK_FLAGS "-undefined dynamic_lookup")
+ENDIF()
+INSTALL(TARGETS threadsmain LIBRARY DESTINATION "${Torch_INSTALL_LIB_SUBDIR}")
+
 if(WIN32)
   add_definitions(-DUSE_WIN_THREADS=1)
 else()
diff --git a/lib/THThread.c b/lib/THThread.c
index 1a680c6..a273600 100644
--- a/lib/THThread.c
+++ b/lib/THThread.c
@@ -1,6 +1,3 @@
-#ifndef TH_THREAD_INC
-#define TH_THREAD_INC
-
 #include <stdlib.h>
 #include <string.h>
 
@@ -85,39 +82,32 @@ int pthread_cond_signal(pthread_cond_t *cond)
 #error no thread system available
 #endif
 
-typedef struct THThread_ {
+struct THThread_ {
   pthread_t id;
   int (*func)(void*);
-  void* data;
-  int status;
-} THThread;
+  THThreadState state;
+};
 
-typedef struct THMutex_{
+struct THMutex_{
   pthread_mutex_t id;
   int refcount;
-} THMutex;
+};
 
-typedef struct THCondition_ {
+struct THCondition_ {
   pthread_cond_t id;
   int refcount;
-} THCondition;
-
-static void* thread_closure(void *data)
-{
-  THThread *thread = data;
-  thread->status = thread->func(thread->data);
-  return NULL;
-}
+};
 
-THThread* THThread_new(int (*func)(void*), void *data)
+THThread* THThread_new(void* (*func)(void*), void *data)
 {
   THThread *self = malloc(sizeof(THThread));
-  self->func = func;
-  self->data = data;
-  self->status = 0;
   if(!self)
     return NULL;
-  if(pthread_create(&self->id, NULL, thread_closure, self)) {
+
+  self->state.data = data;
+  self->state.status = 0;
+
+  if(pthread_create(&self->id, NULL, func, &self->state)) {
     free(self);
     return NULL;
   }
@@ -135,7 +125,7 @@ int THThread_free(THThread *self)
   if(self) {
     if(pthread_join(self->id, NULL))
       return 1;
-    status = self->status;
+    status = self->state.status;
     free(self);
   }
   return status;
@@ -238,5 +228,3 @@ void THCondition_free(THCondition *self)
     }
   }
 }
-
-#endif
diff --git a/lib/THThread.h b/lib/THThread.h
index 0b086fb..008223d 100644
--- a/lib/THThread.h
+++ b/lib/THThread.h
@@ -4,8 +4,12 @@
 typedef struct THThread_ THThread;
 typedef struct THMutex_ THMutex;
 typedef struct THCondition_ THCondition;
+typedef struct THThreadState_ {
+  void* data;
+  int status;
+} THThreadState;
 
-THThread* THThread_new(int (*closure)(void*), void *data);
+THThread* THThread_new(void* (*closure)(void*), void *data);
 long THThread_id(THThread *self);
 int THThread_free(THThread *self);
 
diff --git a/lib/thread-main.c b/lib/thread-main.c
new file mode 100644
index 0000000..344e679
--- /dev/null
+++ b/lib/thread-main.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+#include "THThread.h"
+
+static int runthread(void *code_)
+{
+  char *code = code_;
+  lua_State *L = luaL_newstate();
+
+  if(!L) {
+    printf("THREAD FATAL ERROR: could not create lua state\n");
+    return -1;
+  }
+  luaL_openlibs(L);
+
+  if(luaL_loadstring(L, code)) {
+    printf("FATAL THREAD PANIC: (loadstring) %s\n", lua_tolstring(L, -1, NULL));
+    free(code);
+    lua_close(L);
+    return -1;
+  }
+
+  free(code);
+  if(lua_pcall(L, 0, 0, 0)) {
+    printf("FATAL THREAD PANIC: (pcall) %s\n", lua_tolstring(L, -1, NULL));
+    lua_close(L);
+    return -1;
+  }
+
+  lua_close(L);
+  return 0;
+}
+
+void* THThread_main(void *arg)
+{
+  THThreadState* state = arg;
+  state->status = runthread(state->data);
+  return NULL;
+}
diff --git a/lib/threads.c b/lib/threads.c
index 5f379fe..fbb8d60 100644
--- a/lib/threads.c
+++ b/lib/threads.c
@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <luaT.h>
 #include <string.h>
+#include <dlfcn.h>
 
 #include "THThread.h"
 #include "luaTHRD.h"
@@ -9,34 +10,6 @@
 #include <lua.h>
 #include <lualib.h>
 
-static int newthread(void *code_)
-{
-  char *code = code_;
-  lua_State *L = luaL_newstate();
-
-  if(!L) {
-    printf("THREAD FATAL ERROR: could not create lua state\n");
-    return -1;
-  }
-  luaL_openlibs(L);
-
-  if(luaL_loadstring(L, code)) {
-    printf("FATAL THREAD PANIC: (loadstring) %s\n", lua_tolstring(L, -1, NULL));
-    free(code);
-    lua_close(L);
-    return -1;
-  }
-  free(code);
-  if(lua_pcall(L, 0, 0, 0)) {
-    printf("FATAL THREAD PANIC: (pcall) %s\n", lua_tolstring(L, -1, NULL));
-    lua_close(L);
-    return -1;
-  }
-
-  lua_close(L);
-  return 0;
-}
-
 static int thread_new(lua_State *L)
 {
   THThread *thread = NULL;
@@ -47,11 +20,25 @@ static int thread_new(lua_State *L)
     luaL_error(L, "threads: out of memory");
   memcpy(code_dup, code, len+1);
 
-  thread = THThread_new(newthread, (void*)code_dup);
-  if(!thread)
+  void* lib = dlopen("libthreadsmain.so", RTLD_LAZY|RTLD_LOCAL|RTLD_NODELETE);
+  if (!lib) {
+    free(code_dup);
+    luaL_error(L, "threads: dlopen: %s", dlerror());
+  }
+
+  void* (*thread_main)(void*) = dlsym(lib, "THThread_main");
+  if (!thread_main) {
+    free(code_dup);
+    luaL_error(L, "threads: dlsym: %s", dlerror());
+  }
+
+  thread = THThread_new(thread_main, (void*)code_dup);
+  if(!thread) {
+    free(code_dup);
     luaL_error(L, "threads: thread new failed");
-  luaTHRD_pushudata(L, thread, "threads.Thread");
+  }
 
+  luaTHRD_pushudata(L, thread, "threads.Thread");
   return 1;
 }
 
diff --git a/test/test-threads-error.lua b/test/test-threads-error.lua
new file mode 100644
index 0000000..01bf4dd
--- /dev/null
+++ b/test/test-threads-error.lua
@@ -0,0 +1,17 @@
+local threads = require 'threads'
+
+local t = threads.Threads(1, function()
+    sys = require 'sys'
+end)
+
+-- Trigger an error in an endcallback. The callback is run during lua_close
+-- when the Threads:synchronize method is called from the __gc metamethod.
+-- The error may prevent the thread from terminating before the threads module
+-- and libthreads.so is unloaded. In previous versions of threads this would
+-- cause a segfault.
+
+t:addjob(function()
+	sys.sleep(0.1)
+end, function()
+    error('error from callback')
+end)