Configure dlmalloc USE_LOCKS and USE_SPIN_LOCKS from system_libs.py since they need to configure different in Wasm Workers vs pthreads build modes.

Author: juj

system/lib/dlmalloc.c

@@ -18,15 +18,6 @@
 /* XXX Emscripten Tracing API. This defines away the code if tracing is disabled. */
 #include <emscripten/trace.h>
 
-/* Make malloc() and free() threadsafe by securing the memory allocations with pthread mutexes. */
-#ifdef __EMSCRIPTEN_WASM_WORKERS__
-#define USE_LOCKS 1
-#define USE_SPIN_LOCKS 1 // Wasm Workers does not have the pthread API, so use spinwaiting
-#elif defined(__EMSCRIPTEN_PTHREADS__)
-#define USE_LOCKS 1
-#define USE_SPIN_LOCKS 0 // Ensure we use pthread_mutex_t.
-#endif
-
 #ifndef MALLOC_ALIGNMENT
 #include <stddef.h>
 /* `malloc`ed pointers must be aligned at least as strictly as max_align_t. */

tools/system_libs.py

@@ -1271,6 +1271,8 @@ def __init__(self, **kwargs):
     self.memvalidate = kwargs.pop('memvalidate')
     self.verbose = kwargs.pop('verbose')
     self.is_debug = kwargs.pop('is_debug') or self.memvalidate or self.verbose
+    self.thread_safe = kwargs.pop('thread_safe')
+    self.use_spinlocks = kwargs.pop('use_spinlocks')
 
     super().__init__(**kwargs)
 
@@ -1296,6 +1298,11 @@ def get_cflags(self):
       cflags += ['-DMALLOC_FAILURE_ACTION=', '-DEMSCRIPTEN_NO_ERRNO']
     if self.is_tracing:
       cflags += ['--tracing']
+    # Target dlmalloc multithreading aware implementation if using pthreads or Wasm Workers
+    cflags += [f'-DUSE_LOCKS={self.thread_safe}']
+    # When using Wasm Workers, target spinlocks. Otherwise target pthread mutexes when using pthreads.
+    cflags += [f'-DUSE_SPIN_LOCKS={self.use_spinlocks}']
+
     return cflags
 
   def get_base_name_prefix(self):
@@ -1338,6 +1345,8 @@ def get_default_variation(cls, **kwargs):
       is_tracing=settings.EMSCRIPTEN_TRACING,
       memvalidate='memvalidate' in settings.MALLOC,
       verbose='verbose' in settings.MALLOC,
+      use_spinlocks=settings.WASM_WORKERS,
+      thread_safe=settings.SHARED_MEMORY,
       **kwargs
     )