diff options
Diffstat (limited to 'Documentation/technical/ds.txt')
| -rw-r--r-- | Documentation/technical/ds.txt | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/Documentation/technical/ds.txt b/Documentation/technical/ds.txt index 5a1655a1..afead2f1 100644 --- a/Documentation/technical/ds.txt +++ b/Documentation/technical/ds.txt @@ -1,9 +1,14 @@ PublicInbox::DS - event loop and async I/O base class -Our PublicInbox::DS event loop which powers public-inbox-nntpd -and public-inbox-httpd diverges significantly from the -unmaintained Danga::Socket package we forked from. In fact, -it's probably different from most other event loops out there. +Our PublicInbox::DS event loop which powers most of our long-lived +processes(*) diverges significantly from the unmaintained Danga::Socket +package we forked from. In fact, it's probably different from most +other event loops out there. + +Most notably, it uses one-shot, level-trigger, and edge-trigger mode +modes of kqueue|epoll depending on the situation. + +(*) public-inbox-netd,(-httpd,-imapd,-nntpd,-pop3d,-watch) + lei-daemon Most notably: @@ -14,7 +19,7 @@ Most notably: triggers a call. The lack of read/write callback distinction is driven by the - fact TLS libraries (e.g. OpenSSL via IO::Socket::SSL) may + fact that TLS libraries (e.g. OpenSSL via IO::Socket::SSL) may declare SSL_WANT_READ on SSL_write(), and SSL_WANT_READ on SSL_read(). So we end up having to let each user object decide whether it wants to make read or write calls depending on its @@ -30,7 +35,7 @@ Most notably: Reducing the user-supplied code down to a single callback allows subclasses to keep their logic self-contained. The combination of this change and one-shot wakeups (see below) for bidirectional - data flows make asynchronous code easier to reason about. + data flows makes asynchronous code easier to reason about. Other divergences: @@ -48,7 +53,7 @@ Other divergences: Augmented features: -* obj->write(CODEREF) passes the object itself to the CODEREF +* obj->write(CODEREF) passes the object itself to the CODEREF. Being able to enqueue subroutine calls is a powerful feature in Danga::Socket for keeping linear logic in an asynchronous environment. Unfortunately, each subroutine takes several kilobytes of memory. @@ -81,7 +86,7 @@ New features * IO::Socket::SSL support (for NNTPS, STARTTLS+NNTP, HTTPS) -* dwaitpid (waitpid wrapper) support for reaping dead children +* awaitpid (waitpid wrapper) support for reaping dead children * reliable signal wakeups are supported via signalfd on Linux, EVFILT_SIGNAL on *BSDs via IO::KQueue. |