pytorch/c10/core/impl/LocalDispatchKeySet.cpp
Scott Wolchok dde5b6e177 [PyTorch] Reapply D25547962: Make tls_local_dispatch_key_set inlineable (reapply) (#49763)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49763

This was reverted because it landed in a stack together with
D25542799 (9ce1df079f), which really was broken.
ghstack-source-id: 119063016

Test Plan: CI

Reviewed By: ezyang

Differential Revision: D25685959

fbshipit-source-id: 514d8076eac67c760f119cfebc2ae3d0ddcd4e04
2021-01-06 14:41:43 -08:00

115 lines
3.4 KiB
C++

#include <c10/core/impl/LocalDispatchKeySet.h>
#include <iostream>
namespace c10 {
namespace impl {
/// In the CAFFE2_FB_LIMITED_MOBILE_CAPABILITY build setting,
/// thread_local is not supported.
#ifndef CAFFE2_FB_LIMITED_MOBILE_CAPABILITY
// NB: POD, zero initialized!
thread_local PODLocalDispatchKeySet raw_local_dispatch_key_set;
#else // defined(CAFFE2_FB_LIMITED_MOBILE_CAPABILITY)
PODLocalDispatchKeySet raw_local_dispatch_key_set;
#endif
#ifdef _MSC_VER
LocalDispatchKeySet tls_local_dispatch_key_set() {
return raw_local_dispatch_key_set;
}
#endif // _MSC_VER
void _force_tls_local_dispatch_key_set(LocalDispatchKeySet key_set) {
raw_local_dispatch_key_set = PODLocalDispatchKeySet {
key_set.included_.raw_repr(),
key_set.excluded_.raw_repr()
};
}
// An RAII guard could snapshot and restore the entire state (entire DispatchKeySet) as
// opposed to only snapshotting and restoring the state of its assigned DispatchKeySet.
// I'm not sure which is better. If only the RAII API is used, the two choices are
// not distinguishable.
//
// However, if the guard chooses to snapshot and restore the entire DispatchKeySet,
// the interaction with the non-RAII API changes. Consider this sequence of events:
// - An RAII guard is declared for a particular DispatchKeySet, but snapshots the entire
// current DispatchKeySet.
// - A call to the non-RAII API changes the state for DispatchKeys outside the assigned
// set.
// - The RAII guard goes out of scope, restoring the entire DispatchKeySet it snapshotted
// (which restores the state for its own assigned DispatchKey and wipes out the state
// for the other DispatchKeys set by the non-RAII API).
// RAII API
IncludeDispatchKeyGuard::IncludeDispatchKeyGuard(DispatchKeySet include)
: tls_(&raw_local_dispatch_key_set)
, include_(include - tls_->included()) {
if (!include_.empty()) {
tls_->set_included(tls_->included() | include_);
}
}
IncludeDispatchKeyGuard::~IncludeDispatchKeyGuard() {
if (!include_.empty()) {
tls_->set_included(tls_->included() - include_);
}
}
ExcludeDispatchKeyGuard::ExcludeDispatchKeyGuard(DispatchKeySet exclude)
: tls_(&raw_local_dispatch_key_set)
, exclude_(exclude - tls_->excluded()) {
if (!exclude_.empty()) {
tls_->set_excluded(tls_->excluded() | exclude_);
}
}
ExcludeDispatchKeyGuard::~ExcludeDispatchKeyGuard() {
if (!exclude_.empty()) {
tls_->set_excluded(tls_->excluded() - exclude_);
}
}
// Non-RAII API
// Please prefer using the RAII API. See declarations in LocalDispatchKeySet.h for details.
bool tls_is_dispatch_key_excluded(DispatchKey x) {
return raw_local_dispatch_key_set.excluded().has(x);
}
void tls_set_dispatch_key_excluded(DispatchKey x, bool desired_state) {
auto* tls = &raw_local_dispatch_key_set;
bool current_state = tls->excluded().has(x);
if (desired_state != current_state) {
if (desired_state) {
tls->set_excluded(tls->excluded().add(x));
} else {
tls->set_excluded(tls->excluded().remove(x));
}
}
}
bool tls_is_dispatch_key_included(DispatchKey x) {
return raw_local_dispatch_key_set.included().has(x);
}
void tls_set_dispatch_key_included(DispatchKey x, bool desired_state) {
auto* tls = &raw_local_dispatch_key_set;
bool current_state = tls->included().has(x);
if (desired_state != current_state) {
if (desired_state) {
tls->set_included(tls->included().add(x));
} else {
tls->set_included(tls->included().remove(x));
}
}
}
}} // namespace c10::impl