New log features: indentation and thread switching indication

[bennylp]

Two new features are introduced by this ticket:

1. Indentation

Indentation of log message to give grouping context of the messages. Example:

21:13:35.787   pjsua_call.c  Answering call 1: code=200
21:13:35.787  pjsua_media.c  ...Call 1: updating media..
21:13:35.787  pjsua_media.c  .....Media session call01:0 is destroyed
21:13:35.787  pjsua_media.c  ....Audio channel update..
21:13:35.787  strm0x22f04d8  .....VAD temporarily disabled
21:13:35.788  strm0x22f04d8  .....Encoder stream started
21:13:35.788  strm0x22f04d8  .....Decoder stream started
21:13:35.788    pjsua_app.c  ...Call 1 media 0 [type=audio], status is Active
21:13:35.788  pjsua_media.c  ...Conf disconnect: 2 -x- 0
21:13:35.788  pjsua_media.c  ...Conf connect: 3 --> 0
21:13:35.788  pjsua_media.c  ...Conf connect: 0 --> 3

Use pj_log_push_indent() and pj_log_pop_indent() to use this new feature. The PJ_LOG_HAS_INDENT must be set in the log decoration flag (it is set by default by PJSUA-LIB).

The indentation is applied on per thread basis.

The complete features introduced by this ticket are:

• new functions: pj_log_add_indent(int), pj_log_push_indent(), pj_log_pop_indent()
• new log decor: PJ_LOG_HAS_INDENT
• new macros: PJ_LOG_ENABLE_INDENT (1), PJ_LOG_INDENT_SIZE (1), PJ_LOG_INDENT_CHAR ('.')

Sample code:

#include <pj/log.h>
#define THIS_FILE  "sample.c"

void inner()
{
    PJ_LOG(4,(THIS_FILE, "We're in inner"));
}

void outer()
{
    PJ_LOG(4,(THIS_FILE, "Calling inner"));
    pj_log_push_indent();
    inner();
    pj_log_pop_indent();
}

int main()
{
    pj_log_set_decor(pj_log_get_decor() | PJ_LOG_HAS_INDENT);
    outer();
    return 0;
}

The sample code above will produce:

21:13:35.787       sample.c  Calling inner
21:13:35.787       sample.c  .We're in inner

2. Thread Switch Indication

An exclamation mark will be placed before a log message if the caller thread is different than the caller thread of the previous message.

Example:

21:13:35.787       sample.c  Thread A is calling the log
21:13:35.787       sample.c  ..This one is still from thread A
21:13:35.787       sample.c !Thread B appears (indentation has changed too)
21:13:35.787       sample.c  Thread B again
21:13:35.787       sample.c !..Thread A resumes (indentation changed back)

This feature is controlled by the new PJ_LOG_HAS_THREAD_SWC log decor. It is set by default by PJSUA-LIB.

[bennylp]

(In [3752]) Implemented re #1372: New log features: indentation and thread switching indication

[bennylp]

(In [3753]) Modified the libraries to use the new log indentation feature re #1372