1 | #pragma once |
2 | |
3 | #include <stddef.h> |
4 | #include <cstdint> |
5 | #include <utility> |
6 | #include <atomic> |
7 | #include <Core/Types.h> |
8 | |
9 | /** Allows to count number of simultaneously happening processes or current value of some metric. |
10 | * - for high-level profiling. |
11 | * |
12 | * See also ProfileEvents.h |
13 | * ProfileEvents counts number of happened events - for example, how many times queries was executed. |
14 | * CurrentMetrics counts number of simultaneously happening events - for example, number of currently executing queries, right now, |
15 | * or just current value of some metric - for example, replica delay in seconds. |
16 | * |
17 | * CurrentMetrics are updated instantly and are correct for any point in time. |
18 | * For periodically (asynchronously) updated metrics, see AsynchronousMetrics.h |
19 | */ |
20 | |
21 | namespace CurrentMetrics |
22 | { |
23 | /// Metric identifier (index in array). |
24 | using Metric = size_t; |
25 | using Value = DB::Int64; |
26 | |
27 | /// Get name of metric by identifier. Returns statically allocated string. |
28 | const char * getName(Metric event); |
29 | /// Get text description of metric by identifier. Returns statically allocated string. |
30 | const char * getDocumentation(Metric event); |
31 | |
32 | /// Metric identifier -> current value of metric. |
33 | extern std::atomic<Value> values[]; |
34 | |
35 | /// Get index just after last metric identifier. |
36 | Metric end(); |
37 | |
38 | /// Set value of specified metric. |
39 | inline void set(Metric metric, Value value) |
40 | { |
41 | values[metric].store(value, std::memory_order_relaxed); |
42 | } |
43 | |
44 | /// Add value for specified metric. You must subtract value later; or see class Increment below. |
45 | inline void add(Metric metric, Value value = 1) |
46 | { |
47 | values[metric].fetch_add(value, std::memory_order_relaxed); |
48 | } |
49 | |
50 | inline void sub(Metric metric, Value value = 1) |
51 | { |
52 | add(metric, -value); |
53 | } |
54 | |
55 | /// For lifetime of object, add amout for specified metric. Then subtract. |
56 | class Increment |
57 | { |
58 | private: |
59 | std::atomic<Value> * what; |
60 | Value amount; |
61 | |
62 | Increment(std::atomic<Value> * what_, Value amount_) |
63 | : what(what_), amount(amount_) |
64 | { |
65 | *what += amount; |
66 | } |
67 | |
68 | public: |
69 | Increment(Metric metric, Value amount_ = 1) |
70 | : Increment(&values[metric], amount_) {} |
71 | |
72 | ~Increment() |
73 | { |
74 | if (what) |
75 | what->fetch_sub(amount, std::memory_order_relaxed); |
76 | } |
77 | |
78 | Increment(Increment && old) |
79 | { |
80 | *this = std::move(old); |
81 | } |
82 | |
83 | Increment & operator= (Increment && old) |
84 | { |
85 | what = old.what; |
86 | amount = old.amount; |
87 | old.what = nullptr; |
88 | return *this; |
89 | } |
90 | |
91 | void changeTo(Value new_amount) |
92 | { |
93 | what->fetch_add(new_amount - amount, std::memory_order_relaxed); |
94 | amount = new_amount; |
95 | } |
96 | |
97 | /// Subtract value before destructor. |
98 | void destroy() |
99 | { |
100 | what->fetch_sub(amount, std::memory_order_relaxed); |
101 | what = nullptr; |
102 | } |
103 | }; |
104 | } |
105 | |