added backend_n

README.rst

@@ -147,11 +147,24 @@ Initializes the hash ring. This function must be called after all backends are
 added. The argument is the numbers of replicas the hash ring contains for each
 backend.
 
+INT .hash_string(STRING, ENUM { CRC32, SHA256, RS })
+----------------------------------------------------
+
+Returns the hash of its first argument using the hash
+algorithm defined.
+
 BACKEND .backend()
 ------------------
 
 Returns a backend based on the default hash of the request URL.
 
+BACKEND .backend_n(INT, BOOL, BOOL, INT)
+----------------------------
+
+Returns the n-th backend (first parameter) with respect of altsrv_p (second
+parameter) and respect of its healthy state (third parameter) for the given
+hash (last parameter).
+
 BACKEND .backend_by_int(INT)
 ----------------------------
 
@@ -162,11 +175,14 @@ BACKEND .backend_by_string(STRING)
 ----------------------------------
 
 Returns a backend based on the default hash of its argument.
+DEPRECATED: use .backend_by_int(hash_string()) instead
 
 BACKEND .backend_by_string_hash(STRING, ENUM { CRC32, SHA256, RS })
 -------------------------------------------------------------------
+
 Returns a backend based on the hash of its first argument using the hash
 algorithm defined.
+DEPRECATED: use .backend_by_int(hash_string()) instead
 
 
 LIMITATIONS

src/vmod_vslp.c

@@ -30,6 +30,7 @@
 
 #include <stdlib.h>
 #include <stdint.h>
+#include <stdbool.h>
 #include <arpa/inet.h>
 
 #include "cache/cache.h"
@@ -120,6 +121,21 @@ vmod_vslp_init_hashcircle(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslp
 	vslpdir_init_hashcircle(vslpd->vslpd, replicas);
 }
 
+VCL_INT __match_proto__(td_vslp_vslp_hash_string)
+vmod_vslp_hash_string(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslpd, VCL_STRING s, VCL_ENUM hash_m)
+{
+	uint32_t hash;
+	hash_func hash_fp;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(vslpd, VMOD_VSLP_VSLP_MAGIC);
+
+	hash_fp = vslp_get_hash_fp(hash_m);
+	hash = hash_fp(s ? s : "");
+
+	return (hash);
+}
+
 VCL_BACKEND __match_proto__(td_vslp_vslp_backend)
 vmod_vslp_backend(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslpd)
 {
@@ -139,7 +155,20 @@ vmod_vslp_backend(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslpd)
 	}
 
 	hash = vslpd->vslpd->hash_fp(http->hd[HTTP_HDR_URL].b);
-	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash);
+	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash, 0, true, true);
+
+	return (be);
+}
+
+VCL_BACKEND __match_proto__(td_vslp_vslp_backend_n)
+vmod_vslp_backend_n(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslpd, VCL_INT n, VCL_BOOL altsrv_p, VCL_BOOL healthy,  VCL_INT i)
+{
+	VCL_BACKEND be;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(vslpd, VMOD_VSLP_VSLP_MAGIC);
+
+	be = vslpdir_pick_be(vslpd->vslpd, ctx, i, n, altsrv_p, healthy);
 
 	return (be);
 }
@@ -152,7 +181,7 @@ vmod_vslp_backend_by_int(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vslpd
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	CHECK_OBJ_NOTNULL(vslpd, VMOD_VSLP_VSLP_MAGIC);
 
-	be = vslpdir_pick_be(vslpd->vslpd, ctx, i);
+	be = vslpdir_pick_be(vslpd->vslpd, ctx, i, 0, true, true);
 
 	return (be);
 }
@@ -167,7 +196,7 @@ vmod_vslp_backend_by_string(const struct vrt_ctx *ctx, struct vmod_vslp_vslp *vs
 	CHECK_OBJ_NOTNULL(vslpd, VMOD_VSLP_VSLP_MAGIC);
 
 	hash = vslpd->vslpd->hash_fp(s ? s : "");
-	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash);
+	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash, 0, true, true);
 
 	return (be);
 }
@@ -184,7 +213,7 @@ vmod_vslp_backend_by_string_hash(const struct vrt_ctx *ctx, struct vmod_vslp_vsl
 
 	hash_fp = vslp_get_hash_fp(hash_m);
 	hash = hash_fp(s ? s : "");
-	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash);
+	be = vslpdir_pick_be(vslpd->vslpd, ctx, hash, 0, true, true);
 
 	return (be);
 }

src/vmod_vslp.vcc

@@ -34,7 +34,9 @@ $Method VOID .set_rampup_ratio(REAL)
 $Method VOID .set_rampup_time(DURATION)
 $Method VOID .set_hash(ENUM { CRC32, SHA256, RS })
 $Method VOID .init_hashcircle(INT)
+$Method INT .hash_string(STRING, ENUM { CRC32, SHA256, RS })
 $Method BACKEND .backend()
+$Method BACKEND .backend_n(INT, BOOL, BOOL, INT)
 $Method BACKEND .backend_by_int(INT)
 $Method BACKEND .backend_by_string(STRING)
 $Method BACKEND .backend_by_string_hash(STRING, ENUM { CRC32, SHA256, RS })

src/vslp_dir.c

@@ -378,24 +378,31 @@ vslpdir_any_healthy(struct vslpdir *vslpd)
 	return (retval);
 }
 
-VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, uint32_t hash)
+VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, uint32_t hash,
+		VCL_INT n_retry, VCL_BOOL altsrv_p, VCL_BOOL healthy)
 {
 	VCL_BACKEND be;
-	int chosen, be_choice, restarts_o, restarts, n_retry = 0;
+	int chosen, be_choice, restarts_o = 0, restarts = 0;
 	struct vslp_state state;
 
         CHECK_OBJ_NOTNULL(vslpd, VSLPDIR_MAGIC);
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	AN(ctx->vsl);
 
+	if(altsrv_p)
 		be_choice = (scalbn(random(), -31) > vslpd->altsrv_p);
 
+
+	if(n_retry == 0) {
 		if (ctx->bo) {
 			restarts = restarts_o = ctx->bo->retries;
 		} else {
 			AN(ctx->req);
 			restarts = restarts_o = ctx->req->restarts;
 		}
+	} else {
+		n_retry--;
+	}
 
 	state.picklist = 0;
 	state.vslpd = vslpd;
@@ -421,7 +428,10 @@ VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, ui
 	{
 		n_retry++;
 
+		if(healthy)
 			chosen = vslp_choose_next_healthy(&state, n_retry);
+		else
+			chosen = vslp_choose_next(&state, n_retry);
 
 		if(chosen < 0) {
 			VSLb(ctx->vsl, SLT_Debug,
@@ -444,12 +454,17 @@ VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, ui
 		return NULL;
 	}
 
+	if (! healthy) {
+		AN(be);
+		return (be);
+	}
+
 	if (be->healthy(be, NULL))
 	{
 		if(!vslp_be_healthy(&state, chosen))
 			 be_choice ^= be_choice;
 
-		if(!be_choice)
+		if(altsrv_p && !be_choice)
 		{
 			chosen = vslp_choose_next_healthy(&state, n_retry);
 			if(chosen < 0) {

src/vslp_dir.h

@@ -72,4 +72,5 @@ void vslpdir_lock(struct vslpdir *vslpd);
 void vslpdir_unlock(struct vslpdir *vslpd);
 void vslpdir_expand(struct vslpdir *vslpd, unsigned n);
 unsigned vslpdir_any_healthy(struct vslpdir *vslpd);
-VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, uint32_t hash);
+VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd, const struct vrt_ctx *ctx, uint32_t hash,
+	       VCL_INT n_retry, VCL_BOOL altsrv_p, VCL_BOOL healthy);