When configured, an individual listen socket on a given address is
created for each worker process. This allows to reduce in-kernel lock
contention on configurations with high accept rates, resulting in better
performance. As of now it works on Linux and DragonFly BSD.
Note that on Linux incoming connection requests are currently tied up
to a specific listen socket, and if some sockets are closed, connection
requests will be reset, see https://lwn.net/Articles/542629/. With
nginx, this may happen if the number of worker processes is reduced.
There is no such problem on DragonFly BSD.
Based on previous work by Sepherosa Ziehau and Yingqi Lu.
Two mechanisms are implemented to make it possible to store pointers
in shared memory on Windows, in particular on Windows Vista and later
versions with ASLR:
- The ngx_shm_remap() function added to allow remapping of a shared memory
zone to the address originally used for it in the master process. While
important, it doesn't solve the problem by itself as in many cases it's
not possible to use the address because of conflicts with other
allocations.
- We now create mappings at the same address in all processes by starting
mappings at predefined addresses normally unused by newborn processes.
These two mechanisms combined allow to use shared memory on Windows
almost without problems, including reloads.
Based on the patch by Sergey Brester:
http://mailman.nginx.org/pipermail/nginx-devel/2015-April/006836.html
Similar to ngx_http_file_cache_set_slot(), the last component of file->name
with a fixed length of 10 bytes, as generated in ngx_create_temp_path(), is
used as a source for the names of intermediate subdirectories with each one
taking its own part. Ensure that the sum of specified levels with slashes
fits into the length (ticket #731).
Example of usage:
error_log memory:16m debug;
This allows to configure debug logging with minimum impact on performance.
It's especially useful when rare crashes are experienced under high load.
The log can be extracted from a coredump using the following gdb script:
set $log = ngx_cycle->log
while $log->writer != ngx_log_memory_writer
set $log = $log->next
end
set $buf = (ngx_log_memory_buf_t *) $log->wdata
dump binary memory debug_log.txt $buf->start $buf->end
Initial size as calculated from the number of elements may be bigger
than max_size. If this happens, make sure to set size to max_size.
Reported by Chris West.
Previously, this function checked for connection local address existence
and returned error if it was missing. Now a new address is assigned in this
case making it possible to call this function not only for accepted connections.
It appeared that the NGX_HAVE_AIO_SENDFILE macro was defined regardless of
the "--with-file-aio" configure option and the NGX_HAVE_FILE_AIO macro.
Now they are related.
Additionally, fixed one macro.
This reduces layering violation and simplifies the logic of AIO preread, since
it's now triggered by the send chain function itself without falling back to
the copy filter. The context of AIO operation is now stored per file buffer,
which makes it possible to properly handle cases when multiple buffers come
from different locations, each with its own configuration.
The mtx->wait counter was not decremented if we were able to obtain the lock
right after incrementing it. This resulted in unneeded sem_post() calls,
eventually leading to EOVERFLOW errors being logged, "sem_post() failed
while wake shmtx (75: Value too large for defined data type)".
To close the race, mtx->wait is now decremented if we obtain the lock right
after incrementing it in ngx_shmtx_lock(). The result can become -1 if a
concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does.
However, that only leads to one extra iteration in the next call of
ngx_shmtx_lock().
The use_temp_path http cache feature is now implemented using a separate temp
hierarchy in cache directory. Prefix-based temp files are no longer needed.
The original check for NGX_AGAIN was surplus, since the function returns
only NGX_OK or NGX_ERROR. Now it looks similar to other places.
No functional changes.
In 954867a2f0a6, we switched to using resolver node as the timer event data.
This broke debug event logging.
Replaced now unused ngx_resolver_ctx_t.ident with ngx_resolver_node_t.ident
so that ngx_event_ident() extracts something sensible when accessing
ngx_resolver_node_t as ngx_connection_t.
In 954867a2f0a6, we switched to using resolver node as the
timer event data, so make sure we do not free resolver node
memory until the corresponding timer is deleted.
If a syslog daemon is restarted and the unix socket is used, further logging
might stop to work. In case of send error, socket is closed, forcing
a reconnection at the next logging attempt.
The ngx_cycle->log is used when sending the message. This allows to log syslog
send errors in another log.
Logging to syslog after its cleanup handler has been executed was prohibited.
Previously, this was possible from ngx_destroy_pool(), which resulted in error
messages caused by attempts to write into the closed socket.
The "processing" flag is renamed to "busy" to better match its semantics.
In theory, this can provide a bit better distribution of latencies.
Also it simplifies the code, since ngx_queue_t is now used instead
of custom implementation.
RFC3986 says that, for consistency, URI producers and normalizers
should use uppercase hexadecimal digits for all percent-encodings.
This is also what modern web browsers and other tools use.
Using lowercase hexadecimal digits makes it harder to interact with
those tools in case when use of the percent-encoded URI is required,
for example when $request_uri is part of the cache key.
Signed-off-by: Piotr Sikora <piotr@cloudflare.com>
The check became meaningless after refactoring in 2a92804f4109.
With the loop currently in place, "current" can't be NULL, hence
the check can be dropped.
Additionally, the local variable "current" was removed to
simplify code, and pool->current now used directly instead.
Found by Coverity (CID 714236).
This isn't really important as configuration testing shortly ends with
a process termination which will free all sockets, though Coverity
complains.
Prodded by Coverity (CID 400872).
