/**
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* \file
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* Coop threading
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*
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* Author:
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* Rodrigo Kumpera (kumpera@gmail.com)
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*
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* Copyright 2015 Xamarin, Inc (http://www.xamarin.com)
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* Licensed under the MIT license. See LICENSE file in the project root for full license information.
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*/
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#include <config.h>
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/* enable pthread extensions */
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#ifdef TARGET_MACH
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#define _DARWIN_C_SOURCE
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#endif
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#include <mono/utils/mono-compiler.h>
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#include <mono/utils/mono-threads.h>
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#include <mono/utils/mono-tls.h>
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#include <mono/utils/hazard-pointer.h>
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#include <mono/utils/mono-memory-model.h>
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#include <mono/utils/mono-mmap.h>
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#include <mono/utils/atomic.h>
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#include <mono/utils/mono-time.h>
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#include <mono/utils/mono-counters.h>
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#include <mono/utils/mono-threads-coop.h>
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#include <mono/utils/mono-threads-api.h>
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#include <mono/utils/checked-build.h>
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#include <mono/utils/mono-threads-debug.h>
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#ifdef TARGET_OSX
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#include <mono/utils/mach-support.h>
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#endif
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#ifdef _MSC_VER
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// TODO: Find MSVC replacement for __builtin_unwind_init
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#define SAVE_REGS_ON_STACK g_assert_not_reached ();
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#elif defined (HOST_WASM)
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//TODO: figure out wasm stack scanning
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#define SAVE_REGS_ON_STACK do {} while (0)
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#else
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#define SAVE_REGS_ON_STACK __builtin_unwind_init ();
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#endif
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volatile size_t mono_polling_required;
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// FIXME: This would be more efficient if instead of instantiating the stack it just pushed a simple depth counter up and down,
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// perhaps with a per-thread cookie in the high bits.
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#ifdef ENABLE_CHECKED_BUILD_GC
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// Maintains a single per-thread stack of ints, used to ensure nesting is not violated
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static MonoNativeTlsKey coop_reset_count_stack_key;
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static void
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coop_tls_push (gpointer cookie)
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{
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GArray *stack;
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stack = mono_native_tls_get_value (coop_reset_count_stack_key);
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if (!stack) {
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stack = g_array_new (FALSE, FALSE, sizeof(gpointer));
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mono_native_tls_set_value (coop_reset_count_stack_key, stack);
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}
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g_array_append_val (stack, cookie);
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}
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static void
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coop_tls_pop (gpointer received_cookie)
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{
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GArray *stack;
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gpointer expected_cookie;
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stack = mono_native_tls_get_value (coop_reset_count_stack_key);
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if (!stack || 0 == stack->len)
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mono_fatal_with_history ("Received cookie %p but found no stack at all\n", received_cookie);
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expected_cookie = g_array_index (stack, gpointer, stack->len - 1);
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stack->len --;
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if (0 == stack->len) {
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g_array_free (stack,TRUE);
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mono_native_tls_set_value (coop_reset_count_stack_key, NULL);
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}
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if (expected_cookie != received_cookie)
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mono_fatal_with_history ("Received cookie %p but expected %p\n", received_cookie, expected_cookie);
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}
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#endif
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static void
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check_info (MonoThreadInfo *info, const gchar *action, const gchar *state)
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{
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if (!info)
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g_error ("Cannot %s GC %s region if the thread is not attached", action, state);
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if (!mono_thread_info_is_current (info))
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g_error ("[%p] Cannot %s GC %s region on a different thread", mono_thread_info_get_tid (info), action, state);
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if (!mono_thread_info_is_live (info))
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g_error ("[%p] Cannot %s GC %s region if the thread is not live", mono_thread_info_get_tid (info), action, state);
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}
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static int coop_reset_blocking_count;
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static int coop_try_blocking_count;
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static int coop_do_blocking_count;
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static int coop_do_polling_count;
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static int coop_save_count;
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static void
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mono_threads_state_poll_with_info (MonoThreadInfo *info);
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void
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mono_threads_state_poll (void)
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{
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mono_threads_state_poll_with_info (mono_thread_info_current_unchecked ());
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}
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static void
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mono_threads_state_poll_with_info (MonoThreadInfo *info)
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{
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g_assert (mono_threads_is_blocking_transition_enabled ());
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++coop_do_polling_count;
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if (!info)
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return;
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THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", mono_thread_info_get_tid (info));
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/* Fast check for pending suspend requests */
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if (!(info->thread_state & (STATE_ASYNC_SUSPEND_REQUESTED | STATE_SELF_SUSPEND_REQUESTED)))
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return;
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++coop_save_count;
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mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
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/* commit the saved state and notify others if needed */
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switch (mono_threads_transition_state_poll (info)) {
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case SelfSuspendResumed:
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break;
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case SelfSuspendWait:
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mono_thread_info_wait_for_resume (info);
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break;
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case SelfSuspendNotifyAndWait:
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mono_threads_notify_initiator_of_suspend (info);
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mono_thread_info_wait_for_resume (info);
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break;
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}
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if (info->async_target) {
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info->async_target (info->user_data);
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info->async_target = NULL;
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info->user_data = NULL;
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}
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}
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static volatile gpointer* dummy_global;
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static MONO_NEVER_INLINE
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void*
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return_stack_ptr (gpointer *i)
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{
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dummy_global = i;
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return i;
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}
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static void
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copy_stack_data (MonoThreadInfo *info, gpointer *stackdata_begin)
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{
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MonoThreadUnwindState *state;
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int stackdata_size;
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gpointer dummy;
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void* stackdata_end = return_stack_ptr (&dummy);
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SAVE_REGS_ON_STACK;
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state = &info->thread_saved_state [SELF_SUSPEND_STATE_INDEX];
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stackdata_size = (char*)stackdata_begin - (char*)stackdata_end;
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if (((gsize) stackdata_begin & (SIZEOF_VOID_P - 1)) != 0)
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g_error ("stackdata_begin (%p) must be %d-byte aligned", stackdata_begin, SIZEOF_VOID_P);
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if (((gsize) stackdata_end & (SIZEOF_VOID_P - 1)) != 0)
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g_error ("stackdata_end (%p) must be %d-byte aligned", stackdata_end, SIZEOF_VOID_P);
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if (stackdata_size <= 0)
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g_error ("stackdata_size = %d, but must be > 0, stackdata_begin = %p, stackdata_end = %p", stackdata_size, stackdata_begin, stackdata_end);
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g_byte_array_set_size (info->stackdata, stackdata_size);
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state->gc_stackdata = info->stackdata->data;
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memcpy (state->gc_stackdata, stackdata_end, stackdata_size);
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state->gc_stackdata_size = stackdata_size;
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}
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static gpointer
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mono_threads_enter_gc_safe_region_unbalanced_with_info (MonoThreadInfo *info, gpointer *stackdata);
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gpointer
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mono_threads_enter_gc_safe_region (gpointer *stackdata)
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{
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return mono_threads_enter_gc_safe_region_with_info (mono_thread_info_current_unchecked (), stackdata);
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}
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gpointer
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mono_threads_enter_gc_safe_region_with_info (MonoThreadInfo *info, gpointer *stackdata)
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{
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gpointer cookie;
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if (!mono_threads_is_blocking_transition_enabled ())
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return NULL;
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cookie = mono_threads_enter_gc_safe_region_unbalanced_with_info (info, stackdata);
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#ifdef ENABLE_CHECKED_BUILD_GC
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if (mono_check_mode_enabled (MONO_CHECK_MODE_GC))
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coop_tls_push (cookie);
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#endif
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return cookie;
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}
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gpointer
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mono_threads_enter_gc_safe_region_unbalanced (gpointer *stackdata)
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{
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return mono_threads_enter_gc_safe_region_unbalanced_with_info (mono_thread_info_current_unchecked (), stackdata);
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}
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static gpointer
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mono_threads_enter_gc_safe_region_unbalanced_with_info (MonoThreadInfo *info, gpointer *stackdata)
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{
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if (!mono_threads_is_blocking_transition_enabled ())
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return NULL;
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++coop_do_blocking_count;
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check_info (info, "enter", "safe");
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copy_stack_data (info, stackdata);
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retry:
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++coop_save_count;
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mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
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switch (mono_threads_transition_do_blocking (info)) {
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case DoBlockingContinue:
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break;
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case DoBlockingPollAndRetry:
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mono_threads_state_poll_with_info (info);
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goto retry;
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}
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return info;
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}
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void
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mono_threads_exit_gc_safe_region (gpointer cookie, gpointer *stackdata)
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{
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if (!mono_threads_is_blocking_transition_enabled ())
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return;
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#ifdef ENABLE_CHECKED_BUILD_GC
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if (mono_check_mode_enabled (MONO_CHECK_MODE_GC))
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coop_tls_pop (cookie);
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#endif
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mono_threads_exit_gc_safe_region_unbalanced (cookie, stackdata);
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}
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void
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mono_threads_exit_gc_safe_region_unbalanced (gpointer cookie, gpointer *stackdata)
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{
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MonoThreadInfo *info;
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if (!mono_threads_is_blocking_transition_enabled ())
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return;
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info = (MonoThreadInfo *)cookie;
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check_info (info, "exit", "safe");
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switch (mono_threads_transition_done_blocking (info)) {
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case DoneBlockingOk:
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info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
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break;
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case DoneBlockingWait:
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THREADS_SUSPEND_DEBUG ("state polling done, notifying of resume\n");
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mono_thread_info_wait_for_resume (info);
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break;
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default:
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g_error ("Unknown thread state");
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}
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if (info->async_target) {
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info->async_target (info->user_data);
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info->async_target = NULL;
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info->user_data = NULL;
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}
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}
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void
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mono_threads_assert_gc_safe_region (void)
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{
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MONO_REQ_GC_SAFE_MODE;
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}
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gpointer
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mono_threads_enter_gc_unsafe_region (gpointer *stackdata)
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{
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return mono_threads_enter_gc_unsafe_region_with_info (mono_thread_info_current_unchecked (), stackdata);
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}
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gpointer
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mono_threads_enter_gc_unsafe_region_with_info (THREAD_INFO_TYPE *info, gpointer *stackdata)
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{
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gpointer cookie;
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if (!mono_threads_is_blocking_transition_enabled ())
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return NULL;
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cookie = mono_threads_enter_gc_unsafe_region_unbalanced_with_info (info, stackdata);
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#ifdef ENABLE_CHECKED_BUILD_GC
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if (mono_check_mode_enabled (MONO_CHECK_MODE_GC))
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coop_tls_push (cookie);
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#endif
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return cookie;
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}
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gpointer
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mono_threads_enter_gc_unsafe_region_unbalanced (gpointer *stackdata)
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{
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return mono_threads_enter_gc_unsafe_region_unbalanced_with_info (mono_thread_info_current_unchecked (), stackdata);
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}
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gpointer
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mono_threads_enter_gc_unsafe_region_unbalanced_with_info (MonoThreadInfo *info, gpointer *stackdata)
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{
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if (!mono_threads_is_blocking_transition_enabled ())
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return NULL;
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++coop_reset_blocking_count;
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check_info (info, "enter", "unsafe");
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copy_stack_data (info, stackdata);
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switch (mono_threads_transition_abort_blocking (info)) {
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case AbortBlockingIgnore:
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info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
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return NULL;
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case AbortBlockingIgnoreAndPoll:
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mono_threads_state_poll_with_info (info);
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return NULL;
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case AbortBlockingOk:
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info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
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break;
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case AbortBlockingWait:
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mono_thread_info_wait_for_resume (info);
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break;
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default:
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g_error ("Unknown thread state");
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}
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if (info->async_target) {
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info->async_target (info->user_data);
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info->async_target = NULL;
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info->user_data = NULL;
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}
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return info;
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}
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gpointer
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mono_threads_enter_gc_unsafe_region_cookie (void)
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{
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MonoThreadInfo *info;
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g_assert (mono_threads_is_blocking_transition_enabled ());
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info = mono_thread_info_current_unchecked ();
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check_info (info, "enter (cookie)", "unsafe");
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#ifdef ENABLE_CHECKED_BUILD_GC
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if (mono_check_mode_enabled (MONO_CHECK_MODE_GC))
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coop_tls_push (info);
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#endif
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return info;
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}
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void
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mono_threads_exit_gc_unsafe_region (gpointer cookie, gpointer *stackdata)
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{
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if (!mono_threads_is_blocking_transition_enabled ())
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return;
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#ifdef ENABLE_CHECKED_BUILD_GC
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if (mono_check_mode_enabled (MONO_CHECK_MODE_GC))
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coop_tls_pop (cookie);
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#endif
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mono_threads_exit_gc_unsafe_region_unbalanced (cookie, stackdata);
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}
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void
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mono_threads_exit_gc_unsafe_region_unbalanced (gpointer cookie, gpointer *stackdata)
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{
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if (!mono_threads_is_blocking_transition_enabled ())
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return;
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if (!cookie)
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return;
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mono_threads_enter_gc_safe_region_unbalanced (stackdata);
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}
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void
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mono_threads_assert_gc_unsafe_region (void)
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{
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MONO_REQ_GC_UNSAFE_MODE;
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}
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gboolean
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mono_threads_is_coop_enabled (void)
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{
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#if defined(USE_COOP_GC)
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return TRUE;
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#else
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static int is_coop_enabled = -1;
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if (G_UNLIKELY (is_coop_enabled == -1))
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is_coop_enabled = g_hasenv ("MONO_ENABLE_COOP") ? 1 : 0;
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return is_coop_enabled == 1;
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#endif
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}
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gboolean
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mono_threads_is_blocking_transition_enabled (void)
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{
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#if defined(USE_COOP_GC)
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return TRUE;
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#else
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static int is_blocking_transition_enabled = -1;
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if (G_UNLIKELY (is_blocking_transition_enabled == -1))
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is_blocking_transition_enabled = (g_hasenv ("MONO_ENABLE_COOP") || g_hasenv ("MONO_ENABLE_BLOCKING_TRANSITION")) ? 1 : 0;
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return is_blocking_transition_enabled == 1;
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#endif
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}
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void
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mono_threads_coop_init (void)
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{
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if (!mono_threads_is_coop_enabled () && !mono_threads_is_blocking_transition_enabled ())
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return;
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mono_counters_register ("Coop Reset Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_reset_blocking_count);
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mono_counters_register ("Coop Try Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_try_blocking_count);
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mono_counters_register ("Coop Do Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_do_blocking_count);
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mono_counters_register ("Coop Do Polling", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_do_polling_count);
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mono_counters_register ("Coop Save Count", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_save_count);
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//See the above for what's wrong here.
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#ifdef ENABLE_CHECKED_BUILD_GC
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mono_native_tls_alloc (&coop_reset_count_stack_key, NULL);
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#endif
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}
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void
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mono_threads_coop_begin_global_suspend (void)
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{
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if (mono_threads_is_coop_enabled ())
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mono_polling_required = 1;
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}
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void
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mono_threads_coop_end_global_suspend (void)
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{
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if (mono_threads_is_coop_enabled ())
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mono_polling_required = 0;
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}
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