GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/tracer.h
Date: 2025-06-22 02:36:02
Exec Total Coverage
Lines: 4 5 80.0%
Branches: 1 2 50.0%
Line Branch Exec Source
1 /**
2 * This file is part of the CernVM File System.
3 */
4
5 #ifndef CVMFS_TRACER_H_
6 #define CVMFS_TRACER_H_ 1
7
8 #include <inttypes.h>
9 #include <pthread.h>
10 #include <sys/time.h>
11
12 #include <cstdio>
13 #include <string>
14
15 #include "shortstring.h"
16 #include "util/atomic.h"
17 #include "util/single_copy.h"
18
19 /**
20 * Tracer is a thread-safe logging helper. It uses a ring buffer
21 * and spawns a helper thread, that flushes the messages onto the disk
22 * when necessary. The output file is in csv format. Usually tracing
23 * a message is a lock-free process, which therefore should have minimal
24 * overhead.
25 *
26 * This is _not_ supposed to be a debugging system. It is optimized for
27 * speed and does not try to gather any additional information (like
28 * threadid, status of variables, etc.).
29 *
30 * Csv output is adapted from libcsv.
31 *
32 * \todo If anything goes wrong, the whole thing breaks down on assertion. This
33 * might be not desired behavior.
34 */
35 class Tracer : SingleCopy {
36 public:
37 enum TraceEvents {
38 kEventOpen = 1,
39 kEventOpenDir,
40 kEventReadlink,
41 kEventLookup,
42 kEventStatFs,
43 kEventGetAttr,
44 kEventListAttr,
45 kEventGetXAttr
46 };
47
48 Tracer();
49 ~Tracer();
50
51 void Activate(const int buffer_size, const int flush_threshold,
52 const std::string &trace_file);
53 void Spawn();
54 void Flush();
55 4725280 void inline __attribute__((used)) Trace(const int event,
56 const PathString &path,
57 const std::string &msg) {
58
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 4725280 if (active_)
59 4727744 DoTrace(event, path, msg);
60 4849068 }
61
62 ✗ bool inline __attribute__((used)) IsActive() { return active_; }
63
64 private:
65 /**
66 * Code of the first log line in the trace file.
67 */
68 static const int kEventStart = -1;
69 /**
70 * Code of the last log line in the trace file.
71 */
72 static const int kEventStop = -2;
73 /**
74 * Manual flush
75 */
76 static const int kEventFlush = -3;
77
78 /**
79 * Contents of a single log line.
80 */
81 struct BufferEntry {
82 /**
83 * This is currently with milliseconds precision (using gettimeofday).
84 */
85 timeval time_stamp;
86 /**
87 * arbitrary code, negative codes are reserved for internal use.
88 */
89 int code;
90 PathString path; /**< The path that is subject to the trace */
91 std::string msg;
92 };
93
94 static void *MainFlush(void *data);
95 void GetTimespecRel(const int64_t ms, timespec *ts);
96 int WriteCsvFile(FILE *fp, const std::string &field);
97 int32_t DoTrace(const int event,
98 const PathString &path,
99 const std::string &msg);
100
101 bool active_;
102 bool spawned_;
103 std::string trace_file_;
104 int buffer_size_;
105 int flush_threshold_;
106 BufferEntry *ring_buffer_;
107 /**
108 * Has the same size as the ring buffer. If a message is actually copied to
109 * the ring buffer memory, the respective flag is set to 1. Flags are reset
110 * to 0 by the flush thread.
111 */
112 atomic_int32 *commit_buffer_;
113 pthread_t thread_flush_;
114 pthread_cond_t sig_flush_;
115 pthread_mutex_t sig_flush_mutex_;
116 pthread_cond_t sig_continue_trace_;
117 pthread_mutex_t sig_continue_trace_mutex_;
118 /**
119 * Starts with 0 and gets incremented by each call to trace. Contains the
120 * first non-used sequence number.
121 */
122 atomic_int32 seq_no_;
123 /**
124 * Starts with 0 and gets incremented by the flush thread. Points to the
125 * first non-flushed message. flushed <= seq_no holds.
126 */
127 atomic_int32 flushed_;
128 atomic_int32 terminate_flush_thread_;
129 atomic_int32 flush_immediately_;
130 };
131
132 #endif // CVMFS_TRACER_H_
133