Recognize network-failure errnos as indicating hard connection loss.

Up to now, only ECONNRESET (and EPIPE, in most but not quite all places)
received special treatment in our error handling logic.  This patch
changes things so that related error codes such as ECONNABORTED are
also recognized as indicating that the connection's dead and unlikely
to come back.

We continue to think, however, that only ECONNRESET and EPIPE should be
reported as probable server crashes; the other cases indicate network
connectivity problems but prove little about the server's state.  Thus,
there's no change in the error message texts that are output for such
cases.  The key practical effect is that errcode_for_socket_access()
will report ERRCODE_CONNECTION_FAILURE rather than
ERRCODE_INTERNAL_ERROR for a network failure.  It's expected that this
will fix buildfarm member lorikeet's failures since commit 32a9c0bdf,
as that seems to be due to not treating ECONNABORTED equivalently to
ECONNRESET.

The set of errnos treated this way now includes ECONNABORTED, EHOSTDOWN,
EHOSTUNREACH, ENETDOWN, ENETRESET, and ENETUNREACH.  Several of these
were second-class citizens in terms of their handling in places like
get_errno_symbol(), so upgrade the infrastructure where necessary.

As committed, this patch assumes that all these symbols are defined
everywhere.  POSIX specifies all of them except EHOSTDOWN, but that
seems to exist on all platforms of interest; we'll see what the
buildfarm says about that.

Probably this should be back-patched, but let's see what the buildfarm
thinks of it first.

Fujii Masao and Tom Lane

Discussion: https://postgr.es/m/2621622.1602184554@sss.pgh.pa.us

2 files changed, 30 insertions, 0 deletions

diff --git a/src/include/port.h b/src/include/port.h
index 84bf2c363f5..d25716bf7f8 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -99,6 +99,28 @@ extern void pgfnames_cleanup(char **filenames);
 )
 #endif
 
+/*
+ * This macro provides a centralized list of all errnos that identify
+ * hard failure of a previously-established network connection.
+ * The macro is intended to be used in a switch statement, in the form
+ * "case ALL_CONNECTION_FAILURE_ERRNOS:".
+ *
+ * Note: this groups EPIPE and ECONNRESET, which we take to indicate a
+ * probable server crash, with other errors that indicate loss of network
+ * connectivity without proving much about the server's state.  Places that
+ * are actually reporting errors typically single out EPIPE and ECONNRESET,
+ * while allowing the network failures to be reported generically.
+ */
+#define ALL_CONNECTION_FAILURE_ERRNOS \
+	EPIPE: \
+	case ECONNRESET: \
+	case ECONNABORTED: \
+	case EHOSTDOWN: \
+	case EHOSTUNREACH: \
+	case ENETDOWN: \
+	case ENETRESET: \
+	case ENETUNREACH
+
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index f65f426cdbd..59c7f35e3df 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -369,8 +369,16 @@ extern int	_pgstat64(const char *name, struct stat *buf);
 #define EADDRINUSE WSAEADDRINUSE
 #undef EADDRNOTAVAIL
 #define EADDRNOTAVAIL WSAEADDRNOTAVAIL
+#undef EHOSTDOWN
+#define EHOSTDOWN WSAEHOSTDOWN
 #undef EHOSTUNREACH
 #define EHOSTUNREACH WSAEHOSTUNREACH
+#undef ENETDOWN
+#define ENETDOWN WSAENETDOWN
+#undef ENETRESET
+#define ENETRESET WSAENETRESET
+#undef ENETUNREACH
+#define ENETUNREACH WSAENETUNREACH
 #undef ENOTCONN
 #define ENOTCONN WSAENOTCONN