Instead of having them dump into the trash and initialize it, let's have
the caller initialize a buffer and pass it. This will be convenient to
dump multiple threads at once into a single buffer.
The new function ha_thread_dump() will dump debugging info about all known
threads. The current thread will contain a bit more info. The long-term goal
is to make it possible to use it in signal handlers to improve the accuracy
of some dumps.
The function dumps its output into the trash so as it was trivial to add,
a new "show threads" command appeared on the CLI.
We do have some code paths testing for impossible errors that tend to
be quite confusing, first for maintenance (what to do on such errors,
and how far to guess the bug), second for developers as it tends to
hide the main purpose and expectations of these call places. Also
most of the time impossible errors are ignored by the callers so the
tests are not even usable during debugging.
Let's instead implement a BUG_ON macro which takes a condition, which
if true, will cause a message to be emitted and optionally to crash the
process. Additionally, these calls inserted at various places server as
hints and documentation for developers to know that such conditions
must absolutely not happen.
This is only enabled when DEBUG_STRICT or DEBUG_STRICT_NOCRASH are set.
As its name implies, DEBUG_STRICT_NOCRASH only performs the test but
does not crash, which can be useful to track some checkpoints.
At the moment nothing uses this code.
On recent gcc versions with the null-deref checks, ABORT_NOW() rightfully
emits such a warning. But here it's on purpose. Simply changing the memory
address to 1 makes gcc happy.
When debugging an issue, sometimes it can be useful to be able to use
byte 0 to poison memory areas, resulting in the same effect as a calloc().
This patch changes the default mem_poison_byte to -1 to disable it so that
all positive values are usable.
With HTTP/2, we'll have to support multiplexed streams. A stream is in
fact the largest part of what we currently call a session, it has buffers,
logs, etc.
In order to catch any error, this commit removes any reference to the
struct session and tries to rename most "session" occurrences in function
names to "stream" and "sess" to "strm" when that's related to a session.
The files stream.{c,h} were added and session.{c,h} removed.
The session will be reintroduced later and a few parts of the stream
will progressively be moved overthere. It will more or less contain
only what we need in an embryonic session.
Sample fetch functions and converters will have to change a bit so
that they'll use an L5 (session) instead of what's currently called
"L4" which is in fact L6 for now.
Once all changes are completed, we should see approximately this :
L7 - http_txn
L6 - stream
L5 - session
L4 - connection | applet
There will be at most one http_txn per stream, and a same session will
possibly be referenced by multiple streams. A connection will point to
a session and to a stream. The session will hold all the information
we need to keep even when we don't yet have a stream.
Some more cleanup is needed because some code was already far from
being clean. The server queue management still refers to sessions at
many places while comments talk about connections. This will have to
be cleaned up once we have a server-side connection pool manager.
Stream flags "SN_*" still need to be renamed, it doesn't seem like
any of them will need to move to the session.
A new member has been added to the struct session. It keeps a trace
of what block of code performs a close or a shutdown on a socket, and
in what sequence. This is extremely convenient for post-mortem analysis
where flag combinations and states seem impossible. A new ABORT_NOW()
macro has also been added to make the code immediately segfault where
called.
The new TRACE macro is used almost like fprintf, except that a session
has to be passed instead of the file descriptor. It displays infos about
where it is called, session ptr and id, etc...
