//------------------------------------------------------------------------
// Methods of allocate_root_proxy
//------------------------------------------------------------------------
task& allocate_root_proxy::allocate( size_t size ) {
internal::generic_scheduler* v = governor::local_scheduler();
__TBB_ASSERT( v, "thread did not activate a task_scheduler_init object?" );
#if __TBB_TASK_GROUP_CONTEXT
task_prefix& p = v->innermost_running_task->prefix();
ITT_STACK_CREATE(p.context->itt_caller);
#endif
// New root task becomes part of the currently running task's cancellation context
return v->allocate_task( size, __TBB_CONTEXT_ARG(NULL, p.context) );
}
//------------------------------------------------------------------------
// Methods of allocate_root_with_context_proxy
//------------------------------------------------------------------------
task& allocate_root_with_context_proxy::allocate( size_t size ) const {
internal::generic_scheduler* s = governor::local_scheduler();
__TBB_ASSERT( s, "Scheduler auto-initialization failed?" );
task& t = s->allocate_task( size, __TBB_CONTEXT_ARG(NULL, &my_context) );
// Supported usage model prohibits concurrent initial binding. Thus we do not
// need interlocked operations or fences to manipulate with my_context.my_kind
if ( my_context.my_kind == task_group_context::binding_required ) {
// If we are in the outermost task dispatch loop of a master thread, then
// there is nothing to bind this context to, and we skip the binding part
// treating the context as isolated.
if ( s->my_innermost_running_task == s->my_dummy_task )
my_context.my_kind = task_group_context::isolated;
else
my_context.bind_to( s );
}
ITT_STACK_CREATE(my_context.itt_caller);
return t;
}
//------------------------------------------------------------------------
// Methods of allocate_root_with_context_proxy
//------------------------------------------------------------------------
task& allocate_root_with_context_proxy::allocate( size_t size ) const {
internal::generic_scheduler* v = governor::local_scheduler();
__TBB_ASSERT( v, "thread did not activate a task_scheduler_init object?" );
task_prefix& p = v->innermost_running_task->prefix();
task& t = v->allocate_task( size, __TBB_CONTEXT_ARG(NULL, &my_context) );
// Supported usage model prohibits concurrent initial binding. Thus we do not
// need interlocked operations or fences to manipulate with my_context.my_kind
if ( my_context.my_kind == task_group_context::binding_required ) {
__TBB_ASSERT ( my_context.my_owner, "Context without owner" );
__TBB_ASSERT ( !my_context.my_parent, "Parent context set before initial binding" );
// If we are in the outermost task dispatch loop of a master thread, then
// there is nothing to bind this context to, and we skip the binding part.
if ( v->innermost_running_task != v->dummy_task ) {
// Though the following assignment makes my_context accessible for
// cancelation propagation, we cannot rely on the cancellation being
// propagated into it without taking a global lock. Instead we always
// check the state of my_context's ancestors, and use cancelation
// epoch counters to minimize the depth of inspection.
my_context.my_parent = p.context;
uintptr_t local_count_snapshot = v->local_cancel_count;
// Prevent load of global_cancel_count from being hoisted above store
// to my_context.my_parent and load of local_cancel_count.
__TBB_full_memory_fence();
// The full fence guarantees that if no cancelation propagation was
// detected by the following condition, either my_context's parent
// has correct cancelation state or my_context will receive cancelation
// signal if new cancelation starts after
if ( local_count_snapshot != global_cancel_count ) {
// Another thread is propagating cancellation right now. Make sure
// that my_context's parent gets the cancellation request (if one
// of its ancestors is canceled) before we read it later on.
p.context->propagate_cancellation_from_ancestors();
}
if ( p.context->my_cancellation_requested ) {
// Propagate cancellation state from the parent context
my_context.my_cancellation_requested = 1;
}
}
my_context.my_kind = task_group_context::binding_completed;
}
// else the context either has already been associated with its parent or is isolated
ITT_STACK_CREATE(my_context.itt_caller);
return t;
}
//------------------------------------------------------------------------
// Methods of allocate_root_with_context_proxy
//------------------------------------------------------------------------
task& allocate_root_with_context_proxy::allocate( size_t size ) const {
internal::generic_scheduler* v = governor::local_scheduler();
__TBB_ASSERT( v, "thread did not activate a task_scheduler_init object?" );
task_prefix& p = v->innermost_running_task->prefix();
task& t = v->allocate_task( size, __TBB_CONTEXT_ARG(NULL, &my_context) );
// The supported usage model prohibits concurrent initial binding. Thus we
// do not need interlocked operations or fences here.
if ( my_context.my_kind == task_group_context::binding_required ) {
__TBB_ASSERT ( my_context.my_owner, "Context without owner" );
__TBB_ASSERT ( !my_context.my_parent, "Parent context set before initial binding" );
// If we are in the outermost task dispatch loop of a master thread, then
// there is nothing to bind this context to, and we skip the binding part.
if ( v->innermost_running_task != v->dummy_task ) {
// By not using the fence here we get faster code in case of normal execution
// flow in exchange of a bit higher probability that in cases when cancellation
// is in flight we will take deeper traversal branch. Normally cache coherency
// mechanisms are efficient enough to deliver updated value most of the time.
uintptr_t local_count_snapshot = ((generic_scheduler*)my_context.my_owner)->local_cancel_count;
__TBB_store_with_release(my_context.my_parent, p.context);
uintptr_t global_count_snapshot = __TBB_load_with_acquire(global_cancel_count);
if ( !my_context.my_cancellation_requested ) {
if ( local_count_snapshot == global_count_snapshot ) {
// It is possible that there is active cancellation request in our
// parents chain. Fortunately the equality of the local and global
// counters means that if this is the case it's already been propagated
// to our parent.
my_context.my_cancellation_requested = p.context->my_cancellation_requested;
} else {
// Another thread was propagating cancellation request at the moment
// when we set our parent, but since we do not use locks we could've
// been skipped. So we have to make sure that we get the cancellation
// request if one of our ancestors has been canceled.
my_context.propagate_cancellation_from_ancestors();
}
}
}
my_context.my_kind = task_group_context::binding_completed;
}
// else the context either has already been associated with its parent or is isolated
ITT_STACK_CREATE(my_context.itt_caller);
return t;
}
//------------------------------------------------------------------------
// Methods of allocate_root_with_context_proxy
//------------------------------------------------------------------------
task& allocate_root_with_context_proxy::allocate( size_t size ) const {
internal::generic_scheduler* s = governor::local_scheduler();
__TBB_ASSERT( s, "Scheduler auto-initialization failed?" );
__TBB_ASSERT( &my_context, "allocate_root(context) argument is a dereferenced NULL pointer" );
task& t = s->allocate_task( size, NULL, &my_context );
// Supported usage model prohibits concurrent initial binding. Thus we do not
// need interlocked operations or fences to manipulate with my_context.my_kind
if ( __TBB_load_relaxed(my_context.my_kind) == task_group_context::binding_required ) {
// If we are in the outermost task dispatch loop of a master thread, then
// there is nothing to bind this context to, and we skip the binding part
// treating the context as isolated.
if ( s->master_outermost_level() )
__TBB_store_relaxed(my_context.my_kind, task_group_context::isolated);
else
my_context.bind_to( s );
}
#if __TBB_FP_CONTEXT
if ( __TBB_load_relaxed(my_context.my_kind) == task_group_context::isolated &&
!(my_context.my_version_and_traits & task_group_context::fp_settings) )
my_context.copy_fp_settings( *s->my_arena->my_default_ctx );
#endif
ITT_STACK_CREATE(my_context.itt_caller);
return t;
}