optionally support glibc malloc_info via SIGCONT malloc_info

If run with PERL_INLINE_DIRECTORY for Inline::C support
along with INBOX_DEBUG=malloc_info, we can allow users
to opt-in to compiling extra code to support the glibc
malloc_info(3) function.

We'll also add SIGCONT handler to dump the malloc_info(3)
output to stderr on our daemons.

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 66b916df..9210f111 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -149,6 +149,23 @@ int pi_fork_exec(int in, int out, int err,
 }
 VFORK_SPAWN
 
+# TODO: we may support other mallocs through this parameter
+if (($ENV{INBOX_DEBUG} // '') =~ /\bmalloc_info\b/) {
+        $vfork_spawn .= <<MALLOC_DEBUG;
+#include <malloc.h>
+
+int inbox_malloc_info(int options)
+{
+        int rc = malloc_info(options, stderr);
+
+        return rc == 0 ? TRUE : FALSE;
+}
+MALLOC_DEBUG
+
+        # dump malloc info to stderr on SIGCONT
+        $SIG{CONT} = sub { inbox_malloc_info(0) };
+}
+
 my $inline_dir = $ENV{PERL_INLINE_DIRECTORY};
 $vfork_spawn = undef unless defined $inline_dir && -d $inline_dir && -w _;
 if (defined $vfork_spawn) {