diff options
Diffstat (limited to 'absl/strings/internal/cordz_info.cc')
-rw-r--r-- | absl/strings/internal/cordz_info.cc | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/absl/strings/internal/cordz_info.cc b/absl/strings/internal/cordz_info.cc new file mode 100644 index 00000000..4dec63d5 --- /dev/null +++ b/absl/strings/internal/cordz_info.cc @@ -0,0 +1,138 @@ +// Copyright 2019 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/strings/internal/cordz_info.h" + +#include "absl/base/config.h" +#include "absl/debugging/stacktrace.h" +#include "absl/strings/internal/cord_internal.h" +#include "absl/strings/internal/cordz_handle.h" +#include "absl/strings/internal/cordz_statistics.h" +#include "absl/synchronization/mutex.h" +#include "absl/types/span.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace cord_internal { + +constexpr int CordzInfo::kMaxStackDepth; + +ABSL_CONST_INIT std::atomic<CordzInfo*> CordzInfo::ci_head_{nullptr}; +ABSL_CONST_INIT absl::Mutex CordzInfo::ci_mutex_(absl::kConstInit); + +CordzInfo* CordzInfo::Head(const CordzSnapshot& snapshot) { + ABSL_ASSERT(snapshot.is_snapshot()); + ABSL_ASSERT(snapshot.DiagnosticsHandleIsSafeToInspect(ci_head_unsafe())); + return ci_head_unsafe(); +} + +CordzInfo* CordzInfo::Next(const CordzSnapshot& snapshot) const { + ABSL_ASSERT(snapshot.is_snapshot()); + ABSL_ASSERT(snapshot.DiagnosticsHandleIsSafeToInspect(this)); + ABSL_ASSERT(snapshot.DiagnosticsHandleIsSafeToInspect(ci_next_unsafe())); + return ci_next_unsafe(); +} + +CordzInfo* CordzInfo::TrackCord(CordRep* rep, const CordzInfo* src) { + CordzInfo* ci = new CordzInfo(rep); + if (src) { + ci->parent_stack_depth_ = src->stack_depth_; + memcpy(ci->parent_stack_, src->stack_, sizeof(void*) * src->stack_depth_); + } + ci->Track(); + return ci; +} + +CordzInfo* CordzInfo::TrackCord(CordRep* rep) { + return TrackCord(rep, nullptr); +} + +void CordzInfo::UntrackCord(CordzInfo* cordz_info) { + assert(cordz_info); + if (cordz_info) { + cordz_info->Untrack(); + CordzHandle::Delete(cordz_info); + } +} + +CordzInfo::CordzInfo(CordRep* rep) + : rep_(rep), + stack_depth_(absl::GetStackTrace(stack_, /*max_depth=*/kMaxStackDepth, + /*skip_count=*/1)), + parent_stack_depth_(0), + create_time_(absl::Now()) {} + +CordzInfo::~CordzInfo() { + // `rep_` is potentially kept alive if CordzInfo is included + // in a collection snapshot (which should be rare). + if (ABSL_PREDICT_FALSE(rep_)) { + CordRep::Unref(rep_); + } +} + +void CordzInfo::Track() { + absl::MutexLock l(&ci_mutex_); + + CordzInfo* const head = ci_head_.load(std::memory_order_acquire); + if (head != nullptr) { + head->ci_prev_.store(this, std::memory_order_release); + } + ci_next_.store(head, std::memory_order_release); + ci_head_.store(this, std::memory_order_release); +} + +void CordzInfo::Untrack() { + { + // TODO(b/117940323): change this to assuming ownership instead once all + // Cord logic is properly keeping `rep_` in sync with the Cord root rep. + absl::MutexLock lock(&mutex()); + rep_ = nullptr; + } + + absl::MutexLock l(&ci_mutex_); + + CordzInfo* const head = ci_head_.load(std::memory_order_acquire); + CordzInfo* const next = ci_next_.load(std::memory_order_acquire); + CordzInfo* const prev = ci_prev_.load(std::memory_order_acquire); + + if (next) { + ABSL_ASSERT(next->ci_prev_.load(std::memory_order_acquire) == this); + next->ci_prev_.store(prev, std::memory_order_release); + } + if (prev) { + ABSL_ASSERT(head != this); + ABSL_ASSERT(prev->ci_next_.load(std::memory_order_acquire) == this); + prev->ci_next_.store(next, std::memory_order_release); + } else { + ABSL_ASSERT(head == this); + ci_head_.store(next, std::memory_order_release); + } +} + +void CordzInfo::SetCordRep(CordRep* rep) { + mutex().AssertHeld(); + rep_ = rep; +} + +absl::Span<void* const> CordzInfo::GetStack() const { + return absl::MakeConstSpan(stack_, stack_depth_); +} + +absl::Span<void* const> CordzInfo::GetParentStack() const { + return absl::MakeConstSpan(parent_stack_, parent_stack_depth_); +} + +} // namespace cord_internal +ABSL_NAMESPACE_END +} // namespace absl |