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2019-06-30ds: rely on refcounting to close descriptors
Since we have EPOLL_CTL_DEL implemented for the poll(2) and kqueue backends, we can rely on Perl refcounting to gently close(2) the underlying file descriptors as references get dropped. This may be beneficial in the future if we want to drop a descriptor from the event loop without actually closing it.
2019-06-29dskqxs: more closely match epoll semantics
EV_DISPATCH is actually a better match for EPOLLONESHOT semantics than EV_ONESHOT in that it doesn't require EV_ADD for every mod operation. Blindly using EV_ADD everywhere forces the FreeBSD kernel to do extra allocations up front, so it's best avoided.
2019-06-29http: use bigger, but shorter-lived buffers for pipes
Linux pipes default to 65536 bytes in size, and we want to read external processes as fast as possible now that we don't use Danga::Socket or buffer to heap. However, drop the buffer ASAP if we need to wait on anything; since idle buffers can be idle for eons. This lets other execution contexts can reuse that memory right away.
2019-06-29httpd/async: switch to buffering-as-fast-as-possible
With DS buffering to a temporary file nowadays, applying backpressure to git-http-backend(1) hurts overall memory usage of the system. Instead, try to get git-http-backend(1) to finish as quickly as possible and use edge-triggered notifications to reduce wakeups on our end.
2019-06-29parentpipe: make the ->close call more obvious
We can close directly in event_step without bad side effects, and then we also don't need to take a reason arg from worker_quit, since we weren't logging it anywhere.
2019-06-29parentpipe: document and use one-shot wakeups
The master process only dies once and we close ourselves right away. So it doesn't matter if it's level-triggered or edge-triggered, actually, but one-shot is most consistent with our use and keeps the kernel from doing extra work.
2019-06-29http: support HTTPS (kinda)
It's barely any effort at all to support HTTPS now that we have NNTPS support and can share all the code for writing daemons. However, we still depend on Varnish to avoid hug-of-death situations, so supporting reverse-proxying will be required.
2019-06-29ds: consolidate IO::Socket::SSL checks
We need to be careful about handling EAGAIN on write(2) failures deal with SSL_WANT_READ vs SSL_WANT_WRITE as appropriate.
2019-06-29ds: handle deferred DS->close after timers
Our hacks in EvCleanup::next_tick and EvCleanup::asap were due to the fact "closed" sockets were deferred and could not wake up the event loop, causing certain actions to be delayed until an event fired. Instead, ensure we don't sleep if there are pending sockets to close. We can then remove most of the EvCleanup stuff While we're at it, split out immediate timer handling into a separate array so we don't need to deal with time calculations for the event loop.
2019-06-29listener: use edge-triggered notifications
We don't need extra wakeups from the kernel when we know a listener is already active.
2019-06-29http: use requeue instead of watch_in1
Don't use epoll or kqueue to watch for anything unless we hit EAGAIN, since we don't know if a socket is SSL or not.
2019-06-29ds: move requeue logic over from NNTP
We'll be reusing requeue in other places to reduce trips to the kernel to retrieve "hot" descriptors.
2019-06-29ds: share lazy rbuf handling between HTTP and NNTP
Doing this for HTTP cuts the memory usage of 10K idle-after-one-request HTTP clients from 92 MB to 47 MB. The savings over the equivalent NNTP change in commit 6f173864f5acac89769a67739b8c377510711d49, ("nntp: lazily allocate and stash rbuf") seems down to the size of HTTP requests and the fact HTTP is a client-sends-first protocol where as NNTP is server-sends-first.
2019-06-27watchmaildir: show the current path on spamcheck failures
Knowing which message failed a spam check is tough when I have many Maildirs and don't have a search indexing tool setup for spam mail.
2019-06-27nntp: reduce syscalls for ARTICLE and BODY
Chances are we already have extra buffer space following the expensive LF => CRLF conversion that we can safely append an extra CRLF in those places without incurring a copy of the full string buffer. While we're at it, document where our pain points are in terms of memory usage, since tracking/controlling memory use isn't exactly obvious in high-level languages. Perhaps we should start storing messages in git as CRLF...
2019-06-27mbox: split header and body processing
When dealing with ~30MB messages, we can save another ~30MB by splitting the header and body processing and not appending the body string back to the header. We'll rely on buffering in gzip or kernel (via MSG_MORE) to prevent silly packet sizes.
2019-06-27mbox: use Email::Simple->new to do in-place modifications
Email::Simple->new will split the head from the body in-place, and we can avoid using Email::Simple::body. This saves us from holding an extra copy of the message in memory, and saves us around ~30MB when operating on ~30MB messages.
2019-06-27nntp: rework and simplify art_lookup response
We don't need some of the array elements returned from art_lookup, anymore (and haven't used them in years). We can also shorten the lifetime of the Email::Simple object by relying on the fact Email::Simple->new will modify it's arg if given a SCALARREF and allow us to avoid Email::Simple::body calls. Unfortunately, this doesn't seem to provide any noticeable improvement in memory usage when dealing with a 30+ MB test message, since our previous use of ->body_set('') was saving some memory, but forcing a LF-only body to be CRLF was making Perl allocate extra space for s///sg.
2019-06-26ds: cleanup poll test and avoid clobbering imports
On Linux systems with epoll support, we don't want to be clobbering defined subs in the t/ds-poll.t test; so use OO ->method dispatch instead and require users to explicitly import subs via EXPORT_OK.
2019-06-26Merge remote-tracking branch 'origin/nntp-tls'
* origin/nntp-tls: (59 commits) ds: ->write must not clobber empty wbuf array Makefile: skip DSKQXS in global syntax check ds: reduce overhead of tempfile creation Revert "ci: require IO::KQueue on FreeBSD, for now" ds: reimplement IO::Poll support to look like epoll ds: split out IO::KQueue-specific code daemon: use FreeBSD accept filters on non-NNTP daemon: set TCP_DEFER_ACCEPT on everything but NNTP nntp: send greeting immediately for plain sockets ci: require IO::KQueue on FreeBSD, for now nntp: lazily allocate and stash rbuf ds: flush_write runs ->write callbacks even if closed nntp: simplify long response logic and fix nesting ds: always use EV_ADD with EV_SET nntp: reduce allocations for greeting ds: allow ->write callbacks to syswrite directly daemon: use SSL_MODE_RELEASE_BUFFERS t/nntpd-tls: slow client connection test nntp: call SSL_shutdown in normal cases ds|nntp: use CORE::close on socket ...
2019-06-25searchview: avoid displaying full paths on errors
Displaying full path names of installed modules could expose unnecessary information about user home directory names or other potentially sensitive information. However, displaying a module name could still be useful for diagnosing problems, so map full paths to the relevant part of the path name which is relevant to the package name. Reported-by: Ali Alnubani <alialnu@mellanox.com> https://public-inbox.org/meta/20190611193815.c4uovtlp574bid6x@dcvr/
2019-06-24msgmap: mid_insert: use plain "INSERT" to detect duplicates
"INSERT OR IGNORE" still bumps the auto-increment counter in SQLite, which causes gaps to appear in NNTP article numbering. This bug appeared in v2 repos where V2Writable may call ->add repeatedly on the same message. This bug is apparent with public-inbox-watch and work-in-progress IMAP watchers which may rescan and (attempt to) reinsert the same message on mailbox changes. Most uses of public-inbox-mda were not affected, unless the same message is actually delivered multiple times to the mda. v1 is not affected, either, since deduplication is only based on Message-ID and msgmap never sees the duplicate. Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
2019-06-24ds: ->write must not clobber empty wbuf array
We need to account for ->write(CODE) calls doing ->write(SCALARREF), otherwise flush_write may see the wrong ->{wbuf} field.
2019-06-24ds: reduce overhead of tempfile creation
We end up buffering giant things to the FS sometimes, and open() is not a cheap syscall; so being forced to do it twice to get a file description with O_APPEND is gross when we can just use O_EXCL ourselves and loop on EEXIST.
2019-06-24ds: reimplement IO::Poll support to look like epoll
At least the subset of epoll we use. EPOLLET might be difficult to emulate if we end up using it.
2019-06-24ds: split out IO::KQueue-specific code
We don't need to code multiple event loops or have branches in watch() if we can easily make the IO::KQueue-based interface look like our lower-level epoll_* API.
2019-06-24daemon: use FreeBSD accept filters on non-NNTP
Similar to TCP_DEFER_ACCEPT on Linux, FreeBSD has a 'dataready' accept filter which we can use to reduce wakeups when doing TLS negotiation or plain HTTP. There's also a 'httpready' which we can use for plain HTTP connections.
2019-06-24daemon: set TCP_DEFER_ACCEPT on everything but NNTP
This Linux-specific option can save us some wakeups during the TLS negotiation phase, and it can help with ordinary HTTP, too. Plain NNTP (and in the future, POP3) are the only things which require the server send messages, first.
2019-06-24nntp: send greeting immediately for plain sockets
A tiny write() for the greeting on a just accept()-ed TCP socket won't fail with EAGAIN, so we can avoid the extra epoll syscall traffic with plain sockets.
2019-06-24nntp: lazily allocate and stash rbuf
Allocating a per-client buffer up front is unnecessary and wastes a hash slot. For the majority of (non-malicious) clients, we won't need to store rbuf in a long-lived object associated with a client socket at all. This saves around 10M on 64-bit with 20K connected-but-idle clients.
2019-06-24ds: flush_write runs ->write callbacks even if closed
We may need to rely on cleanup code running in enqueued callbacks, so ensure we call it when flush_write happens.
2019-06-24nntp: simplify long response logic and fix nesting
We can get rid of the {long_res} field and reuse the write buffer ordering logic to prevent nesting of responses from requeue. On FreeBSD, this fixes a problem of callbacks firing twice because kqueue as event_step is now our only callback entry point. There's a slight change in the stdout "logging" format, in that we can no longer distinguish between writes blocked due to slow clients or deferred long responses. Not sure if this affects anybody parsing logs or not, but preserving the old format could prove expensive and not worth the effort.
2019-06-24ds: always use EV_ADD with EV_SET
kqueue EV_ONESHOT semantics are different than epoll EPOLLONESHOT. epoll only disables watches for that event while keeping the item in the rbtree for future EPOLL_CTL_MOD. kqueue removes the watch from the filter set entirely, necessitating the use of EV_ADD for future modifications.
2019-06-24nntp: reduce allocations for greeting
No need to allocate a new PerlIO::scalar filehandle for every client, instead we can now pass the same CODE reference which calls DS->write on a reused string reference.
2019-06-24ds: allow ->write callbacks to syswrite directly
We can bypass buffering when wbuf is empty when it's called from a CODE reference passed to ->write.
2019-06-24daemon: use SSL_MODE_RELEASE_BUFFERS
34K per idle connection adds up to large amounts of memory; especially with the speed of malloc nowadays compared to the cost of cache misses or worse, swapping.
2019-06-24nntp: call SSL_shutdown in normal cases
This is in accordance with TLS standards and will be needed to support session caching/reuse in the future. However, we don't issue shutdown(2) since we know not to inadvertantly share our sockets with other processes.
2019-06-24ds|nntp: use CORE::close on socket
IO::Socket::SSL will try to re-bless back to the original class on TLS negotiation failure. Unfortunately, the original class is 'GLOB', and re-blessing to 'GLOB' takes away all the IO::Handle methods, because Filehandle/IO are a special case in Perl5. Anyways, since we already use syswrite() and sysread() as functions on our socket, we might as well use CORE::close(), as well (and it plays nicely with tied classes).
2019-06-24daemon: map inherited sockets to well-known schemes
I don't want to specify "--listen" in my systemd .service files, so map 563 to NNTPS automatically (and 443 to HTTPS, but HTTPS support doesn't work, yet).
2019-06-24nntp: NNTPS and NNTP+STARTTLS working
It kinda, barely works, and I'm most happy I got it working without any modifications to the main NNTP::event_step callback thanks to the DS->write(CODE) support we inherited from Danga::Socket.
2019-06-24nntp: wait for writability before sending greeting
This will be needed for NNTPS support, since we need to negotiate the TLS connection before writing the greeting and we can reuse the existing buffer layer to enqueue writes.
2019-06-24ds: deal better with FS-related errors IO buffers
Instead of ENOMEM (or fragmentation/swap storms), using tempfile buffers opens us up to filesystem and storage-related errors (e.g. ENOSPC, EFBIG, EIO, EROFS). Log these errors, drop the particular client, and try to limp by with whateve we have left.
2019-06-24allow use of PerlIO layers for filesystem writes
It may make sense to use PerlIO::mmap or PerlIO::scalar for DS write buffering with IO::Socket::SSL or similar (since we can't use MSG_MORE), so that means we need to go through buffering in userspace for the common case; while still being easily compatible with slow clients. And it also simplifies GitHTTPBackend slightly. Maybe it can make sense for HTTP input buffering, too...
2019-06-24nntp: simplify re-arming/requeue logic
We can be smarter about requeuing clients to run and avoid excessive epoll_ctl calls since we can trust event_step to do the right thing depending on the state of the client.
2019-06-24ds: hoist out do_read from NNTP and HTTP
Both NNTP and HTTP have common needs and we can factor out some common code to make dealing with IO::Socket::SSL easier.
2019-06-24http|nntp: be explicit about bytes::length on rbuf
It should not matter because our rbuf is always from a socket without encoding layers, but this makes things easier to follow.
2019-06-24ds: remove pointless exit calls
They're never called; the only way to break out of that loop is the PostEventLoop callback.
2019-06-24evcleanup: replace _run_asap with `event_step' callback
No point in keeping a one-line wrapper sub around.
2019-06-24ds: pass $self to code references
We can reduce the amount of short-lived anonymous subs we create by passing $self to code references.
2019-06-24http: don't pass extra args to PublicInbox::DS::close
YAGNI Followup-to: commit 30ab5cf82b9d47242640f748a0f9a088ca783e32 ("ds: reduce Errno imports and drop ->close reason")