1 // Copyright 2011 Google Inc. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef NINJA_METRICS_H_
16 #define NINJA_METRICS_H_
17 
18 #include <string>
19 #include <vector>
20 
21 #include "util.h"  // For int64_t.
22 
23 /// The Metrics module is used for the debug mode that dumps timing stats of
24 /// various actions.  To use, see METRIC_RECORD below.
25 
26 /// A single metrics we're tracking, like "depfile load time".
27 struct Metric {
28     std::string name;
29     /// Number of times we've hit the code path.
30     int count;
31     /// Total time (in platform-dependent units) we've spent on the code path.
32     int64_t sum;
33 };
34 
35 /// A scoped object for recording a metric across the body of a function.
36 /// Used by the METRIC_RECORD macro.
37 struct ScopedMetric {
38     explicit ScopedMetric(Metric* metric);
39     ~ScopedMetric();
40 
41 private:
42     Metric* metric_;
43     /// Timestamp when the measurement started.
44     /// Value is platform-dependent.
45     int64_t start_;
46 };
47 
48 /// The singleton that stores metrics and prints the report.
49 struct Metrics {
50     Metric* NewMetric(const std::string& name);
51 
52     /// Print a summary report to stdout.
53     void Report();
54 
55 private:
56     std::vector<Metric*> metrics_;
57 };
58 
59 /// Get the current time as relative to some epoch.
60 /// Epoch varies between platforms; only useful for measuring elapsed time.
61 int64_t GetTimeMillis();
62 
63 /// A simple stopwatch which returns the time
64 /// in seconds since Restart() was called.
65 struct Stopwatch {
66   public:
StopwatchStopwatch67     Stopwatch() : started_(0) {}
68 
69     /// Seconds since Restart() call.
70     double Elapsed() const;
71 
RestartStopwatch72     void Restart() { started_ = NowRaw(); }
73 
74   private:
75     uint64_t started_;
76     // Return the current time using the native frequency of the high resolution
77     // timer.
78     uint64_t NowRaw() const;
79 };
80 
81 /// The primary interface to metrics.  Use METRIC_RECORD("foobar") at the top
82 /// of a function to get timing stats recorded for each call of the function.
83 #define METRIC_RECORD(name)                                             \
84     static Metric* metrics_h_metric =                                     \
85             g_metrics ? g_metrics->NewMetric(name) : NULL;                    \
86     ScopedMetric metrics_h_scoped(metrics_h_metric);
87 
88 /// A variant of METRIC_RECORD that doesn't record anything if |condition|
89 /// is false.
90 #define METRIC_RECORD_IF(name, condition)            \
91     static Metric* metrics_h_metric =                  \
92             g_metrics ? g_metrics->NewMetric(name) : NULL; \
93     ScopedMetric metrics_h_scoped((condition) ? metrics_h_metric : NULL);
94 
95 extern Metrics* g_metrics;
96 
97 #endif // NINJA_METRICS_H_
98