| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you 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 |
| // |
| // http://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. |
| #pragma once |
| |
| #include <cstdint> |
| #include <map> |
| #include <mutex> |
| #include <string> |
| |
| #include "kudu/gutil/macros.h" |
| #include "kudu/gutil/map-util.h" |
| #include "kudu/util/locks.h" |
| |
| namespace kudu { |
| |
| // A simple map of constant string names to integer counters. |
| // |
| // Typically, the TRACE_COUNTER_INCREMENT(...) macro defined in |
| // trace.h is used to increment a counter within this map. |
| // |
| // This currently is just a thin wrapper around a spinlocked map, |
| // but if it becomes noticeable in the CPU profile, various optimizations |
| // are plausible. |
| class TraceMetrics { |
| public: |
| TraceMetrics() {} |
| ~TraceMetrics() {} |
| |
| // Internalize the given string by duplicating it into a process-wide |
| // pool. If this string has already been interned, returns a pointer |
| // to a previous instance. Otherwise, copies it into the pool. |
| // |
| // The resulting strings are purposefully leaked, so this should only |
| // be used in cases where the number of unique strings that will be |
| // passed is relatively low (i.e. not user-specified). |
| // |
| // Because 'name' is exposed back to operators, it must be a printable |
| // ASCII string. |
| static const char* InternName(const std::string& name); |
| |
| // Increment the given counter. |
| void Increment(const char* name, int64_t amount); |
| |
| // Return a copy of the current counter map. |
| std::map<const char*, int64_t> Get() const; |
| |
| // Return metric's current value. |
| // |
| // NOTE: the 'name' MUST be the same const char* which is used for |
| // insertion. This is because we do pointer-wise comparison internally. |
| int64_t GetMetric(const char* name) const; |
| |
| private: |
| mutable simple_spinlock lock_; |
| std::map<const char*, int64_t> counters_; |
| |
| DISALLOW_COPY_AND_ASSIGN(TraceMetrics); |
| }; |
| |
| inline void TraceMetrics::Increment(const char* name, int64_t amount) { |
| std::lock_guard<simple_spinlock> l(lock_); |
| counters_[name] += amount; |
| } |
| |
| inline std::map<const char*, int64_t> TraceMetrics::Get() const { |
| std::unique_lock<simple_spinlock> l(lock_); |
| return counters_; |
| } |
| |
| inline int64_t TraceMetrics::GetMetric(const char* name) const { |
| std::lock_guard<simple_spinlock> l(lock_); |
| return FindWithDefault(counters_, name, 0); |
| } |
| |
| } // namespace kudu |