diff options
Diffstat (limited to 'absl/container/internal/hashtablez_sampler.h')
-rw-r--r-- | absl/container/internal/hashtablez_sampler.h | 81 |
1 files changed, 6 insertions, 75 deletions
diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h index 85685f72..d86207f5 100644 --- a/absl/container/internal/hashtablez_sampler.h +++ b/absl/container/internal/hashtablez_sampler.h @@ -47,6 +47,7 @@ #include "absl/base/internal/per_thread_tls.h" #include "absl/base/optimization.h" #include "absl/container/internal/have_sse.h" +#include "absl/profiling/internal/sample_recorder.h" #include "absl/synchronization/mutex.h" #include "absl/utility/utility.h" @@ -57,7 +58,7 @@ namespace container_internal { // Stores information about a sampled hashtable. All mutations to this *must* // be made through `Record*` functions below. All reads from this *must* only // occur in the callback to `HashtablezSampler::Iterate`. -struct HashtablezInfo { +struct HashtablezInfo : public profiling_internal::Sample<HashtablezInfo> { // Constructs the object but does not fill in any fields. HashtablezInfo(); ~HashtablezInfo(); @@ -80,14 +81,6 @@ struct HashtablezInfo { std::atomic<size_t> hashes_bitwise_and; std::atomic<size_t> hashes_bitwise_xor; - // `HashtablezSampler` maintains intrusive linked lists for all samples. See - // comments on `HashtablezSampler::all_` for details on these. `init_mu` - // guards the ability to restore the sample to a pristine state. This - // prevents races with sampling and resurrecting an object. - absl::Mutex init_mu; - HashtablezInfo* next; - HashtablezInfo* dead ABSL_GUARDED_BY(init_mu); - // All of the fields below are set by `PrepareForSampling`, they must not be // mutated in `Record*` functions. They are logically `const` in that sense. // These are guarded by init_mu, but that is not externalized to clients, who @@ -231,73 +224,11 @@ inline HashtablezInfoHandle Sample() { #endif // !ABSL_PER_THREAD_TLS } -// Holds samples and their associated stack traces with a soft limit of -// `SetHashtablezMaxSamples()`. -// -// Thread safe. -class HashtablezSampler { - public: - // Returns a global Sampler. - static HashtablezSampler& Global(); - - HashtablezSampler(); - ~HashtablezSampler(); - - // Registers for sampling. Returns an opaque registration info. - HashtablezInfo* Register(); +using HashtablezSampler = + ::absl::profiling_internal::SampleRecorder<HashtablezInfo>; - // Unregisters the sample. - void Unregister(HashtablezInfo* sample); - - // The dispose callback will be called on all samples the moment they are - // being unregistered. Only affects samples that are unregistered after the - // callback has been set. - // Returns the previous callback. - using DisposeCallback = void (*)(const HashtablezInfo&); - DisposeCallback SetDisposeCallback(DisposeCallback f); - - // Iterates over all the registered `StackInfo`s. Returning the number of - // samples that have been dropped. - int64_t Iterate(const std::function<void(const HashtablezInfo& stack)>& f); - - private: - void PushNew(HashtablezInfo* sample); - void PushDead(HashtablezInfo* sample); - HashtablezInfo* PopDead(); - - std::atomic<size_t> dropped_samples_; - std::atomic<size_t> size_estimate_; - - // Intrusive lock free linked lists for tracking samples. - // - // `all_` records all samples (they are never removed from this list) and is - // terminated with a `nullptr`. - // - // `graveyard_.dead` is a circular linked list. When it is empty, - // `graveyard_.dead == &graveyard`. The list is circular so that - // every item on it (even the last) has a non-null dead pointer. This allows - // `Iterate` to determine if a given sample is live or dead using only - // information on the sample itself. - // - // For example, nodes [A, B, C, D, E] with [A, C, E] alive and [B, D] dead - // looks like this (G is the Graveyard): - // - // +---+ +---+ +---+ +---+ +---+ - // all -->| A |--->| B |--->| C |--->| D |--->| E | - // | | | | | | | | | | - // +---+ | | +->| |-+ | | +->| |-+ | | - // | G | +---+ | +---+ | +---+ | +---+ | +---+ - // | | | | | | - // | | --------+ +--------+ | - // +---+ | - // ^ | - // +--------------------------------------+ - // - std::atomic<HashtablezInfo*> all_; - HashtablezInfo graveyard_; - - std::atomic<DisposeCallback> dispose_; -}; +// Returns a global Sampler. +HashtablezSampler& GlobalHashtablezSampler(); // Enables or disables sampling for Swiss tables. void SetHashtablezEnabled(bool enabled); |