Currently, libpq will wrap each send() call on the connection with
two system calls to mask SIGPIPEs. This results in 3 syscalls instead
of one, and (on Linux) can lead to high contention on the signal
mask locks in threaded apps.
We have a couple of other methods to avoid SIGPIPEs:
sockopt(SO_NOSIGPIPE) and the MSG_NOSIGNAL flag to send().
This change attempts to use these if they're available at compile-
and run-time. If not, we drop back to manipulating the signal mask as
before.
Signed-off-by: Jeremy Kerr j...@ozlabs.org
---
src/interfaces/libpq/fe-connect.c | 39 +
src/interfaces/libpq/fe-secure.c | 83 +-
src/interfaces/libpq/libpq-int.h |2
3 files changed, 106 insertions(+), 18 deletions(-)
diff --git a/src/interfaces/libpq/fe-connect.c
b/src/interfaces/libpq/fe-connect.c
index 7f4ae4c..8265268 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1085,6 +1085,7 @@ keep_going:
/* We will come back to here until there is
while (conn-addr_cur != NULL)
{
struct addrinfo *addr_cur =
conn-addr_cur;
+ int optval;
/* Remember current address for
possible error msg */
memcpy(conn-raddr.addr,
addr_cur-ai_addr,
@@ -1149,6 +1150,44 @@ keep_going:
/* We will come back to here until there is
}
#endif /* F_SETFD */
+ /* We have three methods of blocking
sigpipe during
+* send() calls to this socket:
+*
+* - setsockopt(sock, SO_NOSIGPIPE)
+* - send(sock, ..., MSG_NOSIGNAL)
+* - setting the signal mask to
SIG_IGN during send()
+*
+* The first two reduce the number of
syscalls (for the
+* third, we require three syscalls to
implement a send()),
+* so use them if they're available.
Their availability is
+* flagged in the following members of
PGconn:
+*
+* conn-sigpipe_so - we
have set up SO_NOSIGPIPE
+* conn-sigpipe_flag - we're
specifying MSG_NOSIGNAL
+*
+* If we can use SO_NOSIGPIPE, then set
sigpipe_so here and
+* we don't need to care about anything
else. Otherwise,
+* try MSG_NOSIGNAL by setting
sigpipe_flag. If we get an
+* error with MSG_NOSIGNAL, we clear
the flag and revert
+* to manual masking.
+*/
+ conn-sigpipe_so = false;
+#ifdef MSG_NOSIGNAL
+ conn-sigpipe_flag = true;
+#else /* !MSG_NOSIGNAL */
+ conn-sigpipe_flag = false;
+#endif /* MSG_NOSIGNAL */
+
+#ifdef SO_NOSIGPIPE
+ if (!setsockopt(conn-sock, SOL_SOCKET,
SO_NOSIGPIPE,
+ (char *)optval,
sizeof(optval)))
+ {
+ conn-sigpipe_so = true;
+ conn-sigpipe_flag = false;
+ }
+#endif /* SO_NOSIGPIPE */
+
+
/*
* Start/make connection. This should
not block, since we
* are in nonblock mode. If it does,
well, too bad.
diff --git a/src/interfaces/libpq/fe-secure.c b/src/interfaces/libpq/fe-secure.c
index 13c97ac..949cd0f 100644
--- a/src/interfaces/libpq/fe-secure.c
+++ b/src/interfaces/libpq/fe-secure.c
@@ -122,6 +122,18 @@ static long win32_ssl_create_mutex = 0;
*/
#ifndef WIN32
+
+static inline int sigpipe_masked(PGconn *conn)
+{
+ /* If we're on an SSL connection, we can only use SO_NOSIGPIPE masking.
+* Otherwise, we can handle SO_NOSIGPIPE or the MSG_NOSIGNAL flag */
+#ifdef USE_SSL
+ if (conn-ssl)
+ return conn-sigpipe_so;
+#endif
+ return conn-sigpipe_so || conn-sigpipe_flag;
+}
+
#ifdef
