PostgreSQL Source Code  git master
syslogger.h
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1 /*-------------------------------------------------------------------------
2  *
3  * syslogger.h
4  * Exports from postmaster/syslogger.c.
5  *
6  * Copyright (c) 2004-2017, PostgreSQL Global Development Group
7  *
8  * src/include/postmaster/syslogger.h
9  *
10  *-------------------------------------------------------------------------
11  */
12 #ifndef _SYSLOGGER_H
13 #define _SYSLOGGER_H
14 
15 #include <limits.h> /* for PIPE_BUF */
16 
17 
18 /*
19  * Primitive protocol structure for writing to syslogger pipe(s). The idea
20  * here is to divide long messages into chunks that are not more than
21  * PIPE_BUF bytes long, which according to POSIX spec must be written into
22  * the pipe atomically. The pipe reader then uses the protocol headers to
23  * reassemble the parts of a message into a single string. The reader can
24  * also cope with non-protocol data coming down the pipe, though we cannot
25  * guarantee long strings won't get split apart.
26  *
27  * We use non-nul bytes in is_last to make the protocol a tiny bit
28  * more robust against finding a false double nul byte prologue. But
29  * we still might find it in the len and/or pid bytes unless we're careful.
30  */
31 
32 #ifdef PIPE_BUF
33 /* Are there any systems with PIPE_BUF > 64K? Unlikely, but ... */
34 #if PIPE_BUF > 65536
35 #define PIPE_CHUNK_SIZE 65536
36 #else
37 #define PIPE_CHUNK_SIZE ((int) PIPE_BUF)
38 #endif
39 #else /* not defined */
40 /* POSIX says the value of PIPE_BUF must be at least 512, so use that */
41 #define PIPE_CHUNK_SIZE 512
42 #endif
43 
44 typedef struct
45 {
46  char nuls[2]; /* always \0\0 */
47  uint16 len; /* size of this chunk (counts data only) */
48  int32 pid; /* writer's pid */
49  char is_last; /* last chunk of message? 't' or 'f' ('T' or
50  * 'F' for CSV case) */
51  char data[FLEXIBLE_ARRAY_MEMBER]; /* data payload starts here */
53 
54 typedef union
55 {
57  char filler[PIPE_CHUNK_SIZE];
59 
60 #define PIPE_HEADER_SIZE offsetof(PipeProtoHeader, data)
61 #define PIPE_MAX_PAYLOAD ((int) (PIPE_CHUNK_SIZE - PIPE_HEADER_SIZE))
62 
63 
64 /* GUC options */
65 extern bool Logging_collector;
66 extern int Log_RotationAge;
67 extern int Log_RotationSize;
68 extern PGDLLIMPORT char *Log_directory;
69 extern PGDLLIMPORT char *Log_filename;
70 extern bool Log_truncate_on_rotation;
71 extern int Log_file_mode;
72 
73 extern bool am_syslogger;
74 
75 #ifndef WIN32
76 extern int syslogPipe[2];
77 #else
78 extern HANDLE syslogPipe[2];
79 #endif
80 
81 
82 extern int SysLogger_Start(void);
83 
84 extern void write_syslogger_file(const char *buffer, int count, int dest);
85 
86 #ifdef EXEC_BACKEND
87 extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
88 #endif
89 
90 /*
91  * Name of files saving meta-data information about the log
92  * files currently in use by the syslogger
93  */
94 #define LOG_METAINFO_DATAFILE "current_logfiles"
95 #define LOG_METAINFO_DATAFILE_TMP LOG_METAINFO_DATAFILE ".tmp"
96 
97 #endif /* _SYSLOGGER_H */
NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn()
Definition: syslogger.c:157
int Log_file_mode
Definition: syslogger.c:69
void write_syslogger_file(const char *buffer, int count, int dest)
Definition: syslogger.c:995
bool am_syslogger
Definition: syslogger.c:74
#define PGDLLIMPORT
Definition: c.h:1060
signed int int32
Definition: c.h:294
PipeProtoHeader proto
Definition: syslogger.h:56
bool Log_truncate_on_rotation
Definition: syslogger.c:68
bool Logging_collector
Definition: syslogger.c:63
unsigned short uint16
Definition: c.h:305
int Log_RotationSize
Definition: syslogger.c:65
int syslogPipe[2]
Definition: syslogger.c:112
PGDLLIMPORT char * Log_filename
Definition: syslogger.c:67
#define PIPE_CHUNK_SIZE
Definition: syslogger.h:41
PGDLLIMPORT char * Log_directory
Definition: syslogger.c:66
int Log_RotationAge
Definition: syslogger.c:64
WalTimeSample buffer[LAG_TRACKER_BUFFER_SIZE]
Definition: walsender.c:214
#define pg_attribute_noreturn()
Definition: c.h:146
int SysLogger_Start(void)
Definition: syslogger.c:520