This reverts commit 957ec59571.
As discussed with Emeric, the current syntax is not extensible enough,
this will be turned to a section instead in a forthcoming patch.
This patch adds the new global statement:
ring <name> [desc <desc>] [format <format>] [size <size>] [maxlen <length>]
Creates a named ring buffer which could be used on log line for instance.
<desc> is an optionnal description string of the ring. It will appear on
CLI. By default, <name> is reused to fill this field.
<format> is the log format used when generating syslog messages. It may be
one of the following :
iso A message containing only the ISO date, followed by the text.
The PID, process name and system name are omitted. This is
designed to be used with a local log server.
raw A message containing only the text. The level, PID, date, time,
process name and system name are omitted. This is designed to be
used in containers or during development, where the severity only
depends on the file descriptor used (stdout/stderr). This is
the default.
rfc3164 The RFC3164 syslog message format. This is the default.
(https://tools.ietf.org/html/rfc3164)
rfc5424 The RFC5424 syslog message format.
(https://tools.ietf.org/html/rfc5424)
short A message containing only a level between angle brackets such as
'<3>', followed by the text. The PID, date, time, process name
and system name are omitted. This is designed to be used with a
local log server. This format is compatible with what the systemd
logger consumes.
timed A message containing only a level between angle brackets such as
'<3>', followed by ISO date and by the text. The PID, process
name and system name are omitted. This is designed to be
used with a local log server.
<length> is the maximum length of event message stored into the ring,
including formatted header. If the event message is longer
than <length>, it would be truncated to this length.
<name> is the ring identifier, which follows the same naming convention as
proxies and servers.
<size> is the optionnal size in bytes. Default value is set to BUFSIZE.
Note: Historically sink's name and desc were refs on const strings. But with new
configurable rings a dynamic allocation is needed.
Before this path, they rely directly on ring_write bypassing
a part of the sink API.
Now the maxlen parameter of the log will apply only on the text
message part (and not the header, for this you woud prefer
to use the maxlen parameter on the sink/ring).
sink_write prototype was also reviewed to return the number of Bytes
written to be compliant with the other write functions.
This patch extends the sink_write prototype and code to
handle the rfc5424 and rfc3164 header.
It uses header building tools from log.c. Doing this some
functions/vars have been externalized.
facility and minlevel have been removed from the struct sink
and passed to args at sink_write because they depends of the log
and not of the sink (they remained unused by rest of the code
until now).
These are mostly comments in the code. A few error messages were fixed
and are of low enough importance not to deserve a backport. Some regtests
were also fixed.
The principle is that when emitting a message, if some dropped events
were logged, we first attempt to report this counter before going
further. This is done under an exclusive lock while all logs are
produced under a shared lock. This ensures that the dropped line is
accurately reported and doesn't accidently arrive after a later
event.
This is the most basic type of sink. It pre-registers "stdout" and
"stderr", and is able to use writev() on them. The writev() operation
is locked to avoid mixing outputs. It's likely that the registration
should move somewhere else to take into account the fact that stdout
and stderr are still opened or are closed.
The principle will be to be able to dispatch events to various destinations
called "sinks". This is already done in part in logs where log servers can
be either a UDP socket or a file descriptor. This will be needed with the
new trace subsystem where we may also want to add ring buffers. And it turns
out that all such destinations make sense at all places. Logs may need to be
sent to a TCP server via a ring buffer, or consulted from the CLI. Trace
events may need to be sent to stdout/stderr as well as to remote log servers.
This patch creates a new structure "sink" aiming at addressing these similar
needs. The goal is to merge together what is common to all of them, such as
the output format, the dropped events count, etc, and also keep separately
the target identification (network address, file descriptor). Provisions
were made to have a "waiter" on the sink. For a TCP log server it will be
the task to wake up after writing to the log buffer. For a ring buffer, it
could be the list of watchers on the CLI running a "tail" operation and
waiting for new events. A lock was also placed in the struct since many
operations will require some locking, including the FD ones. The output
formats covers those in use by logs and two extra ones prepending the ISO
time in front of the message (convenient for stdio/buffer).
For now only the generic infrastructure is present, no type-specific
output is implemented. There's the sink_write() function which prepares
and formats a message to be sent, trying hard to avoid copies and only
using pointer manipulation, where the type-specific code just has to be
added. Dropped messages are already counted (for now 100% drop). The
message is put into an iovec array as it will be trivial to use with
file descriptors and sockets.
