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Commit 1226479c authored by Poul-Henning Kamp's avatar Poul-Henning Kamp
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Clean up the HTTP1 fsm and document it with a small dot-graph.

parent fe2ad14c
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Showing with 51 additions and 82 deletions
bin/varnishd/cache/cache.h
View file @ 1226479c
......@@ -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] */
......
bin/varnishd/cache/cache_http1_fsm.c
View file @ 1226479c
......@@ -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;
......
bin/varnishd/cache/cache_session.c
View file @ 1226479c
......@@ -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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