phk at varnish-cache
Aug 7, 2012, 1:06 AM
Post #1 of 1
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[master] 1226479 Clean up the HTTP1 fsm and document it with a small dot-graph.
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commit 1226479c26eb10373d74d98bc0628706b64c3f4d
Author: Poul-Henning Kamp <phk [at] FreeBSD>
Date: Tue Aug 7 08:05:34 2012 +0000
Clean up the HTTP1 fsm and document it with a small dot-graph.
diff --git a/bin/varnishd/cache/cache.h b/bin/varnishd/cache/cache.h
index 831c641..920d067 100644
--- a/bin/varnishd/cache/cache.h
+++ b/bin/varnishd/cache/cache.h
@@ -764,9 +764,11 @@ struct busyobj *VBO_GetBusyObj(struct worker *wrk);
void VBO_DerefBusyObj(struct worker *wrk, struct busyobj **busyobj);
void VBO_Free(struct busyobj **vbo);
-/* cache_center.c [CNT] */
+/* cache_http1_fsm.c [HTTP1] */
+void HTTP1_Session(struct worker *, struct req *);
+
+/* cache_req_fsm.c [FSM] */
int CNT_Request(struct worker *, struct req *);
-void CNT_Session(struct worker *, struct req *);
void CNT_Init(void);
/* cache_cli.c [CLI] */
diff --git a/bin/varnishd/cache/cache_http1_fsm.c b/bin/varnishd/cache/cache_http1_fsm.c
index 586fd50..ae01a00 100644
--- a/bin/varnishd/cache/cache_http1_fsm.c
+++ b/bin/varnishd/cache/cache_http1_fsm.c
@@ -26,42 +26,44 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
- * This file contains the two central state machine for pushing
- * sessions and requests.
+ * This file contains the two central state machine for pushing HTTP1
+ * sessions through their states.
*
- * The first part of the file, entrypoint CNT_Session() and down to
- * the ==== separator, is concerned with sessions. When a session has
- * a request to deal with, it calls into the second half of the file.
- * This part is for all practical purposes HTTP/1.x specific.
+ * The following dot-graph shows the big picture, and the two major
+ * complicating features:
*
- * The second part of the file, entrypoint CNT_Request() and below the
- * ==== separator, is intended to (over time) be(ome) protocol agnostic.
- * We already use this now with ESI:includes, which are for all relevant
- * purposes a different "protocol"
+ * - The blue path is where a request disembarks its worker thread while
+ * waiting for a busy object to become available:
*
- * A special complication is the fact that we can suspend processing of
- * a request when hash-lookup finds a busy objhdr.
+ * - The green path is where we time out waiting for the next request to
+ * arrive, release the worker thread and hand the session to the waiter.
+ *
+ * Render the graph with:
+ * sed -n '/^..DOT/s///p' % | dot -Tps > /tmp/_.ps
+ *
+ *DOT digraph vcl_center {
+ *DOT size="7.2,10.5"
+ *DOT margin="0.5"
+ *DOT center="1"
+ *DOT
+ *DOT acceptor -> http1_wait [label=S_STP_NEWREQ, align=center]
+ *DOT hash -> CNT_Request [label="Busy object\nS_STP_WORKING\nR_STP_LOOKUP"
+ *DOT color=blue]
+ *DOT disembark -> hash [style=dotted, color=blue]
+ *DOT http1_wait -> CNT_Request [label="S_STP_WORKING\nR_STP_START"]
+ *DOT http1_wait -> disembark [label="Session close"]
+ *DOT http1_wait -> disembark [label="Timeout" color=green]
+ *DOT disembark -> waiter [style=dotted, color=green]
+ *DOT waiter -> http1_wait [color=green]
+ *DOT CNT_Request -> disembark
+ *DOT [label="Busy object\nS_STP_WORKING\nR_STP_LOOKUP" color=blue]
+ *DOT CNT_Request -> http1_cleanup
+ *DOT http1_cleanup -> disembark [label="Session close"]
+ *DOT http1_cleanup -> CNT_Request [label="S_STP_WORKING\nR_STP_START"]
+ *DOT http1_cleanup -> http1_wait [label="S_STP_NEWREQ"]
+ *DOT
+ *DOT }
*
- * Since the states are rather nasty in detail, I have decided to embedd
- * a dot(1) graph in the source code comments. So to see the big picture,
- * extract the DOT lines and run though dot(1), for instance with the
- * command:
- * sed -n '/^DOT/s///p' cache/cache_center.c | dot -Tps > /tmp/_.ps
- */
-
-/*
-DOT digraph vcl_center {
-xDOT page="8.2,11.5"
-DOT size="7.2,10.5"
-DOT margin="0.5"
-DOT center="1"
-DOT acceptor [
-DOT shape=hexagon
-DOT label="Request received"
-DOT ]
-DOT ERROR [shape=plaintext]
-DOT RESTART [shape=plaintext]
-DOT acceptor -> first [style=bold,color=green]
*/
#include "config.h"
@@ -73,37 +75,16 @@ DOT acceptor -> first [style=bold,color=green]
#include "cache.h"
-#include "hash/hash_slinger.h"
#include "vcl.h"
-#include "vcli_priv.h"
-#include "vsha256.h"
#include "vtcp.h"
#include "vtim.h"
-#ifndef HAVE_SRANDOMDEV
-#include "compat/srandomdev.h"
-#endif
-
-
/*--------------------------------------------------------------------
- * WAIT
- * Collect the request from the client.
- *
-DOT subgraph xcluster_wait {
-DOT wait [
-DOT shape=box
-DOT label="cnt_sess_wait:\nwait for\ncomplete\nrequest"
-DOT ]
-DOT herding [shape=hexagon]
-DOT wait -> start [label="got req",style=bold,color=green]
-DOT wait -> "SES_Delete()" [label="errors"]
-DOT wait -> herding [label="timeout_linger"]
-DOT herding -> wait [label="fd read_ready"]
-DOT }
+ * Collect a request from the client.
*/
static int
-cnt_sess_wait(struct sess *sp, struct worker *wrk, struct req *req)
+http1_wait(struct sess *sp, struct worker *wrk, struct req *req)
{
int j, tmo;
struct pollfd pfd[1];
@@ -117,7 +98,6 @@ cnt_sess_wait(struct sess *sp, struct worker *wrk, struct req *req)
assert(req->sp == sp);
-
AZ(req->vcl);
AZ(req->obj);
AZ(req->esi_level);
@@ -184,25 +164,16 @@ cnt_sess_wait(struct sess *sp, struct worker *wrk, struct req *req)
/*--------------------------------------------------------------------
* This is the final state, figure out if we should close or recycle
* the client connection
- *
-DOT DONE [
-DOT shape=record
-DOT label="{cnt_done:|Request completed}"
-DOT ]
-DOT ESI_RESP [ shape=hexagon ]
-DOT DONE -> start [label="full pipeline"]
-DOT DONE -> wait
-DOT DONE -> ESI_RESP
*/
-enum cnt_sess_done_ret {
+enum http1_cleanup_ret {
SESS_DONE_RET_GONE,
SESS_DONE_RET_WAIT,
SESS_DONE_RET_START,
};
-static enum cnt_sess_done_ret
-cnt_sess_done(struct sess *sp, struct worker *wrk, struct req *req)
+static enum http1_cleanup_ret
+http1_cleanup(struct sess *sp, struct worker *wrk, struct req *req)
{
CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
@@ -225,7 +196,7 @@ cnt_sess_done(struct sess *sp, struct worker *wrk, struct req *req)
}
sp->t_idle = W_TIM_real(wrk);
- if (req->xid == 0)
+ if (req->xid == 0)
req->t_resp = sp->t_idle;
req->xid = 0;
VSL_Flush(req->vsl, 0);
@@ -271,11 +242,11 @@ cnt_sess_done(struct sess *sp, struct worker *wrk, struct req *req)
*/
void
-CNT_Session(struct worker *wrk, struct req *req)
+HTTP1_Session(struct worker *wrk, struct req *req)
{
int done;
struct sess *sp;
- enum cnt_sess_done_ret sdr;
+ enum http1_cleanup_ret sdr;
CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
CHECK_OBJ_NOTNULL(req, REQ_MAGIC);
@@ -295,7 +266,7 @@ CNT_Session(struct worker *wrk, struct req *req)
SES_Close(sp, SC_REM_CLOSE);
else
SES_Close(sp, SC_TX_ERROR);
- sdr = cnt_sess_done(sp, wrk, req);
+ sdr = http1_cleanup(sp, wrk, req);
assert(sdr == SESS_DONE_RET_GONE);
return;
}
@@ -307,10 +278,6 @@ CNT_Session(struct worker *wrk, struct req *req)
}
while (1) {
- /*
- * Possible entrance states
- */
-
assert(
sp->sess_step == S_STP_NEWREQ ||
req->req_step == R_STP_LOOKUP ||
@@ -321,7 +288,7 @@ CNT_Session(struct worker *wrk, struct req *req)
if (done == 2)
return;
assert(done == 1);
- sdr = cnt_sess_done(sp, wrk, req);
+ sdr = http1_cleanup(sp, wrk, req);
switch (sdr) {
case SESS_DONE_RET_GONE:
return;
@@ -333,12 +300,12 @@ CNT_Session(struct worker *wrk, struct req *req)
req->req_step = R_STP_START;
break;
default:
- WRONG("Illegal enum cnt_sess_done_ret");
+ WRONG("Illegal enum http1_cleanup_ret");
}
}
if (sp->sess_step == S_STP_NEWREQ) {
- done = cnt_sess_wait(sp, wrk, req);
+ done = http1_wait(sp, wrk, req);
if (done)
return;
sp->sess_step = S_STP_WORKING;
diff --git a/bin/varnishd/cache/cache_session.c b/bin/varnishd/cache/cache_session.c
index d67d5ff..41dca5c 100644
--- a/bin/varnishd/cache/cache_session.c
+++ b/bin/varnishd/cache/cache_session.c
@@ -139,7 +139,7 @@ ses_req_pool_task(struct worker *wrk, void *arg)
THR_SetRequest(req);
AZ(wrk->aws->r);
wrk->lastused = NAN;
- CNT_Session(wrk, req);
+ HTTP1_Session(wrk, req);
WS_Assert(wrk->aws);
AZ(wrk->wrw);
if (cache_param->diag_bitmap & 0x00040000) {
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