[master] 8bf2b0a Hold a VCL reference in the debug vmod

[Dridi Boukelmoune]

commit 8bf2b0aee5da016125b5ddd007b9b0d040f1a535
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Sat Dec 5 16:09:14 2015 +0100

    Hold a VCL reference in the debug vmod
    
    By default the reference is released as soon as the VCL goes cold, which
    doesn't harm the existing tests yet allows to cover the new VRT_ref_vcl
    and VRT_rel_vcl functions.
    
    It is possible to ask the vmod to release the reference after a delay.

diff --git a/lib/libvmod_debug/vmod.vcc b/lib/libvmod_debug/vmod.vcc
index dad36ec..42159fb 100644
--- a/lib/libvmod_debug/vmod.vcc
+++ b/lib/libvmod_debug/vmod.vcc
@@ -138,3 +138,7 @@ Mark a workspace as overflowed.
 $Function INT workspace_free(ENUM { client, backend, session, thread })
 
 Find how much unallocated space there is left in a workspace.
+
+$Function VOID vcl_release_delay(DURATION)
+
+Hold a reference to the VCL when it goes cold for the given delay.
diff --git a/lib/libvmod_debug/vmod_debug.c b/lib/libvmod_debug/vmod_debug.c
index 9b3449c..91b49c7 100644
--- a/lib/libvmod_debug/vmod_debug.c
+++ b/lib/libvmod_debug/vmod_debug.c
@@ -28,6 +28,7 @@
 
 #include "config.h"
 
+#include <pthread.h>
 #include <stdlib.h>
 #include <stdio.h>
 
@@ -46,6 +47,8 @@ struct priv_vcl {
 	uintptr_t		exp_cb;
 };
 
+VCL_DURATION vcl_release_delay = 0.0;
+
 VCL_VOID __match_proto__(td_debug_panic)
 vmod_panic(VRT_CTX, const char *str, ...)
 {
@@ -280,14 +283,38 @@ event_warm(VRT_CTX)
 		return (-1);
 	}
 
+	VRT_ref_vcl(ctx);
 	return (0);
 }
 
+static void*
+cooldown_thread(void *priv)
+{
+	struct vrt_ctx ctx;
+
+	AN(priv);
+	INIT_OBJ(&ctx, VRT_CTX_MAGIC);
+	ctx.vcl = (struct vcl*)priv;
+
+	VTIM_sleep(vcl_release_delay);
+	VRT_rel_vcl(&ctx);
+	return (NULL);
+}
+
 static int
 event_cold(VRT_CTX)
 {
+	pthread_t thread;
 
 	VSL(SLT_Debug, 0, "%s: VCL_EVENT_COLD", VCL_Name(ctx->vcl));
+
+	if (vcl_release_delay == 0.0) {
+		VRT_rel_vcl(ctx);
+		return (0);
+	}
+
+	AZ(pthread_create(&thread, NULL, cooldown_thread, ctx->vcl));
+	AZ(pthread_detach(thread));
 	return (0);
 }
 
@@ -379,3 +406,12 @@ vmod_workspace_overflow(VRT_CTX, VCL_ENUM which)
 
 	WS_MarkOverflow(ws);
 }
+
+void
+vmod_vcl_release_delay(VRT_CTX, VCL_DURATION delay)
+{
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	assert(delay > 0.0);
+	vcl_release_delay = delay;
+}