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/*****************************************************************************/
/*
Throttle.c
Request "throttling" is a term adopted to describe controlling the number of
concurrent requests that can be processing against any specified path at any
one time. Requests in excess of this value are then FIFO queued up to an
optional limit waiting for a being-processed request to conclude allowing the
next queued request to continue processing again. This is primarily intended
to limit concurrent resource-intensive script execution but could be applied to
*any* resource path. Here's one dictionary description.
throttle n 1: a valve that regulates the supply of fuel to the engine
[syn: accelerator, throttle valve] 2: a pedal that controls the throttle
valve; "he stepped on the gas" [syn: accelerator, accelerator pedal, gas
pedal, gas, gun] v 1: place limits on; "restrict the use of this parking
lot" [syn: restrict, restrain, trammel, limit, bound, confine] 2: squeeze
the throat of; "he tried to strangle his opponent" [syn: strangle,
strangulate] 3: reduce the air supply; of carburetors [syn: choke]
This is applied to a path (or paths) using the mapping SET THROTTLE= rule.
This rule allows a maximum concurrent number of requests to be specified, and
optionally a maximum number of queued requests. When the maximum queued
requests is exceeded the client receives a 503 (server too busy) status. Empty
or zero parameters may be included between the commas.
throttle=from[/per-user][,to,resume,busy,timeout-queue,timeout-busy]
throttle=n1[/u1][,n2,n3,n4,to1,to2]
o from (n1) concurrent requests before queuing begins
o per-user (u1) concurrent requests per (authenticated) user
o to (n2) queuing continues up to this value, when the queue FIFOs
o resume (n3) FIFO continues to this value, where queuing begins again
o busy (n4) absolute maximum concurrent requests before 503 "busy"
o t/o-queue (to1) period before a queued request is processed
o t/o-busy (to2) period before a queued request is 503 "busy"ed
When a throttle rule is loaded it is checked for "sensible" values. Basically
this means that each successive value is larger than it's predecessor.
DESCRIPTION
-----------
o If 'from' (n1) is exceeded then begin to queue. Actively processing
requests does not increase, queue length does.
o If 'per-user' (u1) is non-zero the value regulates the number of
concurrently processing requests for any one authenticated user. Even though
the 'from' value may allow processing if 'per-user' would be exceeded the
request is queued.
o If 'to' (n2) is specified and exceeded then begin to FIFO requests from
the queue into processing. Queue length does not increase (new are being put
onto the queue, previous being taken off of the other end of the queue), but
number processing now begins to increase.
o If 'resume' (n3) is specified this acts as an absolute control on all
request PROCESSING associated with the path. After this value the number of
requests actively being processed does not increase but queue length again
does.
o If 'busy' (n4) is exceeded ALWAYS immediately generate a 503 "busy".
o If 'timeout-queue' (to1) is specified this causes queued requests
exceeding the period to be FIFOed from the queue into processing unless the
'resume' (n3) limit would be exceeded. If this would be exceeded they remain
in the queue (potentially indefinitely, or until they FIFO off the queue, or
until timeout-busy (to2) occurs).
o If 'timeout-busy' (to2) is specified queued requests exceeding the period
are immediately terminated with a 503 "busy" status. A 'timeout-busy' only
begins after the expiry of any 'timeout-queue'.
PER-USER THROTTLING
-------------------
If the concurrent processing value ('from') has a second, slash-delimited
integer, this serves to limit the number of authenticated user-associated
requests that can be concurrently processing.
throttle=n1/u1[,n2,n3,n4,to1,to2]
When a request is available for processing the associated remote user name is
checked for activity against the queue. The 'u1' (or user throttle value) is a
limit on that user name's concurrent processing. If it would exceed the
specified value the request is queued until the number of requests processing
drops below the 'u1' value. All other values in the throttle rule are applied
as for non-per-user throttling.
NOTE: the user name used for comparison purposes is the authenticated remote
user (same as the CGI variable value REMOTE_USER). This can be for any realm.
Of course the same string can be used to represent different users within
different authentication realms and so care should be exercised that per-user
throttling does not span realms otherwise unexpected (and incorrect) throttling
may occur for distinct users. If an unauthenticated request is matched against
the throttle rule (i.e. there is no authorization rule matching the request
path) the client has a 500 (server error) response returned. Obviously
per-user throttling must have a remote user name to throttle against and this
is a configuration issue.
EXAMPLES
--------
1) throttle=10
Requests up to 10 are concurrently processed. When 10 is reached further
requests are queued to server capacity.
2) throttle=10,20
Concurrent requests to 10 are processed immediately. From 11 to 20 requests
are queued. After 20 all requests are queued but also result in a request
FIFOing off the queue to be processed (queue length is static, number being
processed increases to server capacity).
3) throttle=15,30,40
Concurrent requests up to 15 are immediately processed. Requests 16 through to
30 are queued, while 31 to 40 requests result in the new requests being queued
and waiting requests being FIFOed into processing. Concurrent requests from 41
onwards are again queued, in this scenario to server capacity.
4) throttle=10,20,30,40
Concurrent requests up to 10 are immediately processed. Requests 11 through
to 20 will be queued. Concurrent requests from 21 to 30 are queued too, but at
the same time waiting requests are FIFOed from the queue (resulting in 10 (n1)
+ 10 (n3-n2) = 20 being processed). From 31 onwards requests are just queued.
Up to 40 concurrent requests may be against the path before all new requests
are immediately returned with a 503 "busy" status. With this scenario no more
than 20 can be concurrently processed with 20 concurrently queued.
5) throttle=10,,,30
Concurrent requests up to 10 are processed. When 10 is reached requests are
queued up to request 30. When request 31 arrives it is immediately given a 503
"busy" status.
6) throttle=10,20,30,40,00:02:00
This is basically the same as scenario 4) but with a resume-on-timeout of two
minutes. If there are currently 15 (or 22 or 28) requests (n1 exceeded, n3
still within limit) the queued requests will begin processing on timeout.
Should there be 32 processing (n3 has reached limit) the request will continue
to sit in the queue. The timeout would not be reset.
7) throttle=15,30,40,,,00:03:00
This is basically the same as scenario 3) but with a busy-on-timeout of three
minutes. When the timeout expires the request is immediately dequeued with a
503 "busy" status.
8) throttle=10/1
Concurrent requests up to 10 are processed. The requests must be of
authenticated users. Each authenticated user is allowed to execute at most one
concurrent request against this path. When 10 is reached, or if less than 10
users are currently executing requests, then further requests are queued to
server capacity.
9) throttle=10/1,,,,,00:03:00
This is basically the same as scenario 8) but with a busy-on-timeout of three
minutes. When the timeout expires any requests still queued against the user
name is immediately dequeued with a 503 "busy" status.
IMPLEMENTATION
--------------
Request throttling is implemented by the MAPURL.C rule loading providing the
SET THROTTLE= rule parameters against the path, AS WELL AS counting the number
of such paths in the rules. This number is stored along with the maxima and is
used as an index into, as well as to set up, a dynamically allocated array of
structures used to support the concurrent usage tracking and queuing against
that particular path.
Per-user throttling is accomplished by maintaining a list of per-user data
structures associated with each throttle rule that is used to track the number
of requests currently processing and queued against each authenticated user
name attempting to access the path. The list is searched each time the
fundamental throttle structure needs to decide on processing/queueing a
request. This list expands dynamically against demand and is periodically
garbage-collected when the underlying throttle structure is quiescent.
When path mapping SETs a throttle maximum against the request's path the
associated index number is used to select the corresponding element of the
usage structure array. Simple and reasonably efficient. RULE RELOADING could
present a problem with this schema ... but doesn't. The array can grow in size
to accomodate a new rule load with additional throttles, but will never shrink.
(being based on an array index, not a pointer makes this possible). This
allows existing requests with buffered indices to (somewhat) correctly access
the array and be (somewhat) correctly processed. If the actual paths
represented by array elements change there may be some "confusion" in what the
processing and queuing represents. This could possibly result in some
resources temporarily being inappropriately throttled but this gradually
filters out of the functionality as associated requests conclude. There are no
fatal implications (that I can see, anyway) in this scheme.
VERSION HISTORY
---------------
22-MAR-2014 MGD add accounting throttle totals (supports WASDmon)
18-SEP-2006 MGD bugfix; ThrottleReport() column alignment of 'busy' and
'total' percentages in second row of per-path statistics
04-JUL-2006 MGD use PercentOf32() for more accurate percentages
25-MAY-2005 MGD ThrottleControl() provide TERMINATE/RELEASE
selected on username or script name
19-MAY-2005 MGD per-user throttling
06-OCT-2004 MGD reset rqPathSet.ThrottleSet appropriately
20-JUL-2003 MGD revise reporting format
04-AUG-2001 MGD support module WATCHing,
fix end throttle call to RequestExecutePostThrottle()
18-MAY-2001 MGD bugfix; exceeding the point where we should start to FIFO
(jfp@altavista.com)
08-MAY-2001 MGD modify throttle parameter meanings and functionality
08-APR-2001 MGD add 'queue-length' to throttling
13-MAR-2001 MGD initial development
*/
/*****************************************************************************/
#ifdef WASD_VMS_V7
#undef _VMS__V6__SOURCE
#define _VMS__V6__SOURCE
#undef __VMS_VER
#define __VMS_VER 70000000
#undef __CRTL_VER
#define __CRTL_VER 70000000
#endif
/* standard C header files */
#include <ctype.h>
#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
/* VMS related header files */
#include <descrip.h>
#include <ssdef.h>
#include <stsdef.h>
/* application header files */
#include "wasd.h"
#define WASD_MODULE "THROTTLE"
/* reset the request 'path set' data */
#define REQUEST_RESET_THROTTLE(rqptr) \
rqptr->rqPathSet.ThrottleSet = false; \
rqptr->rqPathSet.ThrottleBusy = \
rqptr->rqPathSet.ThrottleFrom = \
rqptr->rqPathSet.ThrottleIndex = \
rqptr->rqPathSet.ThrottlePerUser = \
rqptr->rqPathSet.ThrottleResume = \
rqptr->rqPathSet.ThrottleTo = \
rqptr->rqPathSet.ThrottleTimeoutBusy = \
rqptr->rqPathSet.ThrottleTimeoutQueue = 0;
/******************/
/* global storage */
/******************/
int ThrottleBusyMetricTotal,
ThrottleBusyMetricTotal503,
ThrottleTotal;
THROTTLE_STRUCT *ThrottleArray;
/********************/
/* external storage */
/********************/
#ifdef DBUG
extern BOOL Debug;
#else
#define Debug 0
#endif
extern int InstanceNumber;
extern char ErrorSanityCheck[],
ServerHostPort[],
SoftwareID[];
extern ACCOUNTING_STRUCT *AccountingPtr;
extern CONFIG_STRUCT Config;
extern MAPPING_META *MappingMetaPtr;
extern MSG_STRUCT Msgs;
extern WATCH_STRUCT Watch;
/*****************************************************************************/
/*
(Re)initialize the global throttle structure array.
This will not upset any per-user structure lists pointed at because it's an
effective realloc() preserving the data already present.
*/
ThrottleInit ()
{
int idx;
THROTTLE_STRUCT *tsptr;
/*********/
/* begin */
/*********/
if (WATCH_MODULE(WATCH_MOD_THROTTLE))
WatchThis (WATCHALL, WATCH_MOD_THROTTLE, "ThrottleInit() !UL !UL",
ThrottleTotal, MappingMetaPtr->ThrottleTotal);
if (ThrottleTotal < MappingMetaPtr->ThrottleTotal)
ThrottleTotal = MappingMetaPtr->ThrottleTotal;
if (!ThrottleTotal) return (SS$_NORMAL);
ThrottleArray = (THROTTLE_STRUCT*)
VmRealloc (ThrottleArray, ThrottleTotal*sizeof(THROTTLE_STRUCT), FI_LI);
/* in case this is a mapping rule reload reset all the counters */
ThrottleZero ();
}
/*****************************************************************************/
/*
Zero the accumulators associated with the throttle structure array.
*/
ThrottleZero ()
{
int idx;
THROTTLE_STRUCT *tsptr;
/*********/
/* begin */
/*********/
if (WATCH_MODULE(WATCH_MOD_THROTTLE))
WatchThis (WATCHALL, WATCH_MOD_THROTTLE, "ThrottleZero()");
for (idx = 0; idx < ThrottleTotal; idx++)
{
tsptr = &ThrottleArray[idx];
tsptr->MaxProcessingCount =
tsptr->MaxQueuedCount =
tsptr->Total503Count =
tsptr->TotalCount =
tsptr->TotalFiFoCount =
tsptr->TotalQueuedCount =
tsptr->TotalTimeoutBusyCount =
tsptr->TotalTimeoutQueueCount = 0;
}
ThrottleMonitorReset ();
}
/*****************************************************************************/
/*
Called by HttpdTick() each minute or when there is no more server activity.
*/
ThrottleMonitorReset ()
{
int idx;
THROTTLE_STRUCT *tsptr;
THROTTLE_PER_USER_STRUCT *tpuptr, *nextuser;
/*********/
/* begin */
/*********/
if (WATCH_MODULE(WATCH_MOD_THROTTLE))
WatchThis (WATCHALL, WATCH_MOD_THROTTLE, "ThrottleMonitorReset()");
InstanceMutexLock (INSTANCE_MUTEX_HTTPD);
AccountingPtr->ThrottleBusyMetric =
ThrottleBusyMetricTotal =
ThrottleBusyMetricTotal503 = 0;
AccountingPtr->CurrentThrottleProcessing[InstanceNumber] =
AccountingPtr->CurrentThrottleQueued[InstanceNumber] = 0;
/* zeroing upsets the 'currently' data, recalculate just in case */
for (idx = 0; idx < ThrottleTotal; idx++)
{
tsptr = &ThrottleArray[idx];
AccountingPtr->CurrentThrottleProcessing[InstanceNumber] +=
tsptr->CurrentProcessingCount;
AccountingPtr->CurrentThrottleQueued[InstanceNumber] +=
tsptr->CurrentQueuedCount;
/* garbage-collect per-user structures on a quiescent throttle path */
if (!tsptr->CurrentProcessingCount &&
!tsptr->CurrentQueuedCount)
{
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (tpuptr->CurrentQueuedCount ||
tpuptr->CurrentProcessingCount)
ErrorNoticed (NULL, SS$_BUGCHECK, ErrorSanityCheck, FI_LI);
nextuser = tpuptr->NextUserPtr;
VmFree (tpuptr, FI_LI);
tpuptr = nextuser;
}
tsptr->FirstUserPtr = NULL;
tsptr->CurrentPerUserCount = 0;
}
}
InstanceMutexUnLock (INSTANCE_MUTEX_HTTPD);
}
/*****************************************************************************/
/*
The request path having a maximum concurrent request limit set has resulted in
a call to this function before actually processing the request. If the request
is stalled by queueing then return SS$_RETRY, if it can continue immediately
then return SS$_CONTINUE. See description at the beginning of this module for
an explanation of the algroithm used in this function.
*/
int ThrottleBegin (REQUEST_STRUCT *rqptr)
{
BOOL ProcessRequest,
QueueRequest;
char *cptr;
double fScratch;
THROTTLE_STRUCT *tsptr, *root_tsptr;
THROTTLE_PER_USER_STRUCT *tpuptr;
/*********/
/* begin */
/*********/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "ThrottleBegin()");
ThrottleBusyMetricTotal++;
if (ThrottleBusyMetricTotal503)
{
/* must update the metric here to potentially reduce the metric */
fScratch = (double)ThrottleBusyMetricTotal503 * 100.0 /
(double)ThrottleBusyMetricTotal;
InstanceMutexLock (INSTANCE_MUTEX_HTTPD);
AccountingPtr->ThrottleBusyMetric = (int)fScratch;
if (modf (fScratch, &fScratch) >= 0.5)
AccountingPtr->ThrottleBusyMetric++;
InstanceMutexUnLock (INSTANCE_MUTEX_HTTPD);
}
tsptr = &ThrottleArray[rqptr->rqPathSet.ThrottleIndex];
if (rqptr->rqPathSet.ThrottlePerUser)
{
/************/
/* per-user */
/************/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE,
"per-user:!AZ", rqptr->RemoteUser);
if (!rqptr->RemoteUser[0])
{
if (WATCHING (rqptr, WATCH_REQUEST))
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE per-user NO USER (authorization)");
REQUEST_RESET_THROTTLE(rqptr)
rqptr->rqResponse.HttpStatus = 500;
ErrorGeneral (rqptr, MsgFor(rqptr,MSG_HTTP_500), FI_LI);
return (SS$_ABORT);
}
/* note that this is being throttled on a per-user basis */
rqptr->ThrottlePerUser = true;
/* look for a per-user entry */
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (!strcmp (rqptr->RemoteUser, tpuptr->RemoteUser)) break;
tpuptr = tpuptr->NextUserPtr;
}
if (!tpuptr)
{
/* didn't find one, look for a currently unused entry */
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (!tpuptr->CurrentQueuedCount &&
!tpuptr->CurrentProcessingCount) break;
tpuptr = tpuptr->NextUserPtr;
}
if (tpuptr)
{
/* initialize the reused entry data */
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "reused");
strzcpy (tpuptr->RemoteUser,
rqptr->RemoteUser,
sizeof(tpuptr->RemoteUser));
tpuptr->CurrentQueuedCount =
tpuptr->CurrentProcessingCount =
tpuptr->TotalCount = 0;
}
}
if (!tpuptr)
{
/* didn't find one, add a new entry to the list */
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "new");
tpuptr = (THROTTLE_PER_USER_STRUCT*)VmGet
(sizeof(THROTTLE_PER_USER_STRUCT));
/* insert the new entry at the head of the list */
tpuptr->NextUserPtr = tsptr->FirstUserPtr;
tsptr->FirstUserPtr = tpuptr;
/* initialize the new entry data */
strzcpy (tpuptr->RemoteUser,
rqptr->RemoteUser,
sizeof(tpuptr->RemoteUser));
tsptr->CurrentPerUserCount++;
if (tsptr->CurrentPerUserCount > tsptr->MaxPerUserCount)
tsptr->MaxPerUserCount = tsptr->CurrentPerUserCount;
}
tpuptr->TotalCount++;
}
else
{
rqptr->ThrottlePerUser = false;
tpuptr = NULL;
}
/******************/
/* check throttle */
/******************/
tsptr->TotalCount++;
/* throttle=from[/user],to,resume,busy,t/o-queue,t/o-busy */
ProcessRequest = QueueRequest = false;
/* if it can be processed immediately */
if (tsptr->CurrentProcessingCount <
rqptr->rqPathSet.ThrottleFrom)
ProcessRequest = true;
else
/* if it can be queued */
if (!rqptr->rqPathSet.ThrottleBusy ||
tsptr->CurrentQueuedCount +
tsptr->CurrentProcessingCount <
rqptr->rqPathSet.ThrottleBusy)
{
/* queue it up, perhaps we'll also be FIFOing */
QueueRequest = true;
/* if exceeding the point where we should start to FIFO */
if (rqptr->rqPathSet.ThrottleTo &&
tsptr->CurrentQueuedCount >=
rqptr->rqPathSet.ThrottleTo -
rqptr->rqPathSet.ThrottleFrom)
{
/* if still under any limit imposed on FIFO processing */
if (!rqptr->rqPathSet.ThrottleResume ||
tsptr->CurrentProcessingCount <
(rqptr->rqPathSet.ThrottleResume -
rqptr->rqPathSet.ThrottleTo) +
rqptr->rqPathSet.ThrottleFrom)
ProcessRequest = true;
}
}
if (WATCHING (rqptr, WATCH_REQUEST))
{
/*********/
/* watch */
/*********/
if (ProcessRequest && QueueRequest)
cptr = "->QUEUE->";
else
if (ProcessRequest)
cptr = "PROCESS";
else
if (QueueRequest)
cptr = "->QUEUE";
else
cptr = "BUSY";
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE set:!UL,!UL,!UL,!UL current:!UL,!UL !AZ",
rqptr->rqPathSet.ThrottleFrom,
rqptr->rqPathSet.ThrottleTo,
rqptr->rqPathSet.ThrottleResume,
rqptr->rqPathSet.ThrottleBusy,
tsptr->CurrentProcessingCount,
tsptr->CurrentQueuedCount,
cptr);
}
if (ProcessRequest && tpuptr)
{
/******************/
/* check per-user */
/******************/
if (tpuptr->CurrentProcessingCount >=
rqptr->rqPathSet.ThrottlePerUser)
{
ProcessRequest = false;
QueueRequest = true;
}
if (WATCHING (rqptr, WATCH_REQUEST))
{
if (ProcessRequest)
cptr = "PROCESS";
else
cptr = "->QUEUE";
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE user:!AZ per:!UL current:!UL,!UL !AZ",
tpuptr->RemoteUser,
rqptr->rqPathSet.ThrottlePerUser,
tpuptr->CurrentProcessingCount,
tpuptr->CurrentQueuedCount,
cptr);
}
}
/* this queue code section must precede the process code section */
if (QueueRequest)
{
/*********/
/* queue */
/*********/
tsptr->TotalQueuedCount++;
tsptr->CurrentQueuedCount++;
if (tsptr->CurrentQueuedCount > tsptr->MaxQueuedCount)
tsptr->MaxQueuedCount = tsptr->CurrentQueuedCount;
if (tpuptr) tpuptr->CurrentQueuedCount++;
InstanceMutexLock (INSTANCE_MUTEX_HTTPD);
AccountingPtr->ThrottleTotalQueued++;
AccountingPtr->CurrentThrottleQueued[InstanceNumber]++;
InstanceMutexUnLock (INSTANCE_MUTEX_HTTPD);
/* the list entry data becomes a pointer to the request structure */
rqptr->ThrottleListEntry.DataPtr = (void*)rqptr;
/* add entry to the tail of the waiting list (FIFO) */
ListAddTail (&tsptr->QueuedList, &rqptr->ThrottleListEntry,
LIST_ENTRY_TYPE_THROTTLE);
if (rqptr->rqPathSet.ThrottleTimeoutQueue ||
rqptr->rqPathSet.ThrottleTimeoutBusy)
HttpdTimerSet (rqptr, TIMER_THROTTLE, 0);
/* if this was not a FIFO operation then return here */
if (!ProcessRequest) return (SS$_RETRY);
/****************/
/* FIFO process */
/****************/
/* release the head of the queued requests (note reuse of 'rqptr') */
rqptr = (REQUEST_STRUCT*)(tsptr->QueuedList.HeadPtr->DataPtr);
ThrottleRelease (rqptr, NULL, true);
return (SS$_RETRY);
}
/* this process code section must follow the queue code section */
if (ProcessRequest)
{
/***********/
/* process */
/***********/
tsptr->CurrentProcessingCount++;
if (tsptr->CurrentProcessingCount > tsptr->MaxProcessingCount)
tsptr->MaxProcessingCount = tsptr->CurrentProcessingCount;
if (tpuptr) tpuptr->CurrentProcessingCount++;
InstanceMutexLock (INSTANCE_MUTEX_HTTPD);
AccountingPtr->ThrottleTotalProcessed++;
AccountingPtr->CurrentThrottleProcessing[InstanceNumber]++;
InstanceMutexUnLock (INSTANCE_MUTEX_HTTPD);
return (SS$_CONTINUE);
}
/************/
/* too busy */
/************/
REQUEST_RESET_THROTTLE(rqptr)
tsptr->Total503Count++;
rqptr->rqResponse.HttpStatus = 503;
ErrorGeneral (rqptr, MsgFor(rqptr,MSG_GENERAL_TOO_BUSY), FI_LI);
/* update to increase the metric */
ThrottleBusyMetricTotal503++;
fScratch = (double)ThrottleBusyMetricTotal503 * 100.0 /
(double)ThrottleBusyMetricTotal;
InstanceMutexLock (INSTANCE_MUTEX_HTTPD);
AccountingPtr->ThrottleTotalBusy++;
AccountingPtr->ThrottleBusyMetric = (int)fScratch;
if (modf (fScratch, &fScratch) >= 0.5) AccountingPtr->ThrottleBusyMetric++;
InstanceMutexUnLock (INSTANCE_MUTEX_HTTPD);
return (SS$_ABORT);
}
/*****************************************************************************/
/*
The request path having a maximum concurrent request limit set has resulted in
a call to this function at the end of processing the request. Adjust the
concurrent processing counter and check if there are any requests queued
waiting for processing. If not just return. If there is/are then remove the
front of the list (FIFO) and call the AST function address stored when it was
originally queued to continue processing. See description above for further
detail on "throttling" request processing.
*/
ThrottleEnd (REQUEST_STRUCT *rqptr)
{
int status;
LIST_ENTRY *leptr;
THROTTLE_STRUCT *tsptr;
THROTTLE_PER_USER_STRUCT *tpuptr;
/*********/
/* begin */
/*********/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE,
"ThrottleEnd() !&F", &ThrottleEnd);
tsptr = &ThrottleArray[rqptr->rqPathSet.ThrottleIndex];
if (rqptr->ThrottlePerUser)
{
/* look for the per-user entry */
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (!strcmp (rqptr->RemoteUser, tpuptr->RemoteUser)) break;
tpuptr = tpuptr->NextUserPtr;
}
if (!tpuptr)
ErrorNoticed (rqptr, SS$_BUGCHECK, ErrorSanityCheck, FI_LI);
}
else
tpuptr = NULL;
/* careful, these counters can get scrambled during a mapping reload */
if (tsptr->CurrentProcessingCount)
tsptr->CurrentProcessingCount--;
if (tpuptr && tpuptr->CurrentProcessingCount)
tpuptr->CurrentProcessingCount--;
InstanceGblSecDecrLong (&AccountingPtr->CurrentThrottleProcessing);
if (WATCHING (rqptr, WATCH_REQUEST))
{
if (tpuptr)
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE user:!AZ per:!UL current:!UL,!UL END",
tpuptr->RemoteUser,
rqptr->rqPathSet.ThrottlePerUser,
tpuptr->CurrentProcessingCount,
tpuptr->CurrentQueuedCount);
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE set:!UL,!UL,!UL,!UL current:!UL,!UL END",
rqptr->rqPathSet.ThrottleFrom,
rqptr->rqPathSet.ThrottleTo,
rqptr->rqPathSet.ThrottleResume,
rqptr->rqPathSet.ThrottleBusy,
tsptr->CurrentProcessingCount,
tsptr->CurrentQueuedCount);
}
REQUEST_RESET_THROTTLE(rqptr)
/* if there are no requests waiting to be made active */
if (!tsptr->CurrentQueuedCount) return;
/********************/
/* find one to FIFO */
/********************/
if (rqptr->ThrottlePerUser)
{
/************/
/* per-user */
/************/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "per-user");
/* scan the list of throttled requests */
leptr = tsptr->QueuedList.HeadPtr;
while (leptr)
{
/* note the continued REUSE of 'rqptr'! */
rqptr = (REQUEST_STRUCT*)leptr->DataPtr;
/* look for this per-user entry and check it's processing count */
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (!strcmp (rqptr->RemoteUser, tpuptr->RemoteUser))
{
/* set to null if this user will exceed processing limit */
if (tpuptr->CurrentProcessingCount >=
rqptr->rqPathSet.ThrottlePerUser) tpuptr = NULL;
/* have hit the user so drop this search */
break;
}
/* go to the next per-user entry */
tpuptr = tpuptr->NextUserPtr;
}
/* if found a user entry that could use some more processing */
if (tpuptr) break;
/* go to the next throttled request */
leptr = leptr->NextPtr;
}
if (!leptr) tpuptr = NULL;
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "!&B!-!&? \r\r!AZ",
tpuptr, tpuptr ? rqptr->RemoteUser : "");
/**************************/
/* if none could be found */
/**************************/
if (!tpuptr) return;
}
else
{
/* just FIFO the head of list, note the REUSE of 'rqptr'! */
rqptr = (REQUEST_STRUCT*)(tsptr->QueuedList.HeadPtr->DataPtr);
tpuptr = NULL;
}
/**************/
/* release it */
/**************/
ListRemove (&tsptr->QueuedList, &rqptr->ThrottleListEntry);
/* if no process elbow-room (should only be after sysadmin intervention) */
if (rqptr->rqPathSet.ThrottleResume &&
tsptr->CurrentProcessingCount >=
(rqptr->rqPathSet.ThrottleResume -
rqptr->rqPathSet.ThrottleTo) +
rqptr->rqPathSet.ThrottleFrom) return;
/* release the head of the queued requests (FIFO) */
ThrottleRelease (rqptr, tpuptr, true);
}
/*****************************************************************************/
/*
The HTTPd supervisor has called this function on a throttle timeout. If it's a
"process" timeout then, then check if there is an absolute limit on
concurrently processed requests, if not then just send it on it's way to the
previously buffered next function, otherwise it's a 503 "busy". If it a "busy"
timeout generate a 503 "busy" and the send it to request run-down!
*/
ThrottleTimeout (REQUEST_STRUCT *rqptr)
{
LIST_ENTRY *eptr;
THROTTLE_STRUCT *tsptr;
/*********/
/* begin */
/*********/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "ThrottleTimeout()");
tsptr = &ThrottleArray[rqptr->rqPathSet.ThrottleIndex];
if (WATCHING (rqptr, WATCH_REQUEST))
WatchThis (WATCHITM(rqptr), WATCH_REQUEST, "THROTTLE timeout !AZ",
rqptr->rqPathSet.ThrottleTimeoutQueue ? "QUEUE" : "BUSY");
if (rqptr->rqPathSet.ThrottleTimeoutQueue)
{
/**********************/
/* timeout to process */
/**********************/
tsptr->TotalTimeoutQueueCount++;
/* if to be processed but limited by absolute maximum on processing */
if (rqptr->rqPathSet.ThrottleResume &&
tsptr->CurrentProcessingCount >=
(rqptr->rqPathSet.ThrottleResume -
rqptr->rqPathSet.ThrottleTo) +
rqptr->rqPathSet.ThrottleFrom)
{
/* can't begin processing, just sit and wait on the queue */
if (rqptr->rqPathSet.ThrottleTimeoutBusy)
{
/* this time do not use the process timeout */
rqptr->rqPathSet.ThrottleTimeoutQueue = 0;
HttpdTimerSet (rqptr, TIMER_THROTTLE, 0);
}
else
HttpdTimerSet (rqptr, TIMER_OUTPUT, 0);
return;
}
/* remove the entry from the queue to begin processing */
ThrottleRelease (rqptr, NULL, true);
return;
}
/*******************/
/* timeout to busy */
/*******************/
tsptr->TotalTimeoutBusyCount++;
/* remove the entry from the queue to be terminated with 503 "busy" */
ThrottleRelease (rqptr, NULL, false);
}
/*****************************************************************************/
/*
Remove the request specified by 'rqptr' from the appropriate throttled path's
queue. If 'ToProcess' declare an AST to recommence it's processing. If to
be taken off the queue and discarded generate a 503 "busy" status explicitly
call RequestEnd() as an AST. By the time this function is called it has been
decided whether to process or terminate the particular request.
*/
ThrottleRelease
(
REQUEST_STRUCT *rqptr,
THROTTLE_PER_USER_STRUCT *tpuptr,
BOOL ToProcess
)
{
THROTTLE_STRUCT *tsptr;
/*********/
/* begin */
/*********/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE, "ThrottleRelease()");
tsptr = &ThrottleArray[rqptr->rqPathSet.ThrottleIndex];
/* ThrottleEnd() can supply the 'tpuptr' saving a search here */
if (!tpuptr && rqptr->ThrottlePerUser)
{
/* look for a per-user entry */
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
if (!strcmp (rqptr->RemoteUser, tpuptr->RemoteUser)) break;
tpuptr = tpuptr->NextUserPtr;
}
if (!tpuptr)
ErrorNoticed (rqptr, SS$_BUGCHECK, ErrorSanityCheck, FI_LI);
}
if (WATCHING (rqptr, WATCH_REQUEST))
{
if (tpuptr)
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE user:!AZ per:!UL current:!UL,!UL !AZ",
tpuptr->RemoteUser,
rqptr->rqPathSet.ThrottlePerUser,
tpuptr->CurrentProcessingCount,
tpuptr->CurrentQueuedCount,
ToProcess ? "PROCESS" : "BUSY");
WatchThis (WATCHITM(rqptr), WATCH_REQUEST,
"THROTTLE set:!UL,!UL,!UL,!UL current:!UL,!UL !AZ",
rqptr->rqPathSet.ThrottleFrom,
rqptr->rqPathSet.ThrottleTo,
rqptr->rqPathSet.ThrottleResume,
rqptr->rqPathSet.ThrottleBusy,
tsptr->CurrentProcessingCount,
tsptr->CurrentQueuedCount,
ToProcess ? "PROCESS" : "BUSY");
}
ListRemove (&tsptr->QueuedList, &rqptr->ThrottleListEntry);
/* careful, these counters can get scrambled during a mapping reload */
if (tsptr->CurrentQueuedCount) tsptr->CurrentQueuedCount--;
if (tpuptr && tpuptr->CurrentQueuedCount) tpuptr->CurrentQueuedCount--;
InstanceGblSecDecrLong (&AccountingPtr->CurrentThrottleQueued);
if (ToProcess)
{
/***********/
/* process */
/***********/
/* declare an AST for the next function to be performed */
SysDclAst (&RequestExecutePostThrottle, rqptr);
tsptr->TotalFiFoCount++;
tsptr->CurrentProcessingCount++;
if (tsptr->CurrentProcessingCount > tsptr->MaxProcessingCount)
tsptr->MaxProcessingCount = tsptr->CurrentProcessingCount;
if (tpuptr) tpuptr->CurrentProcessingCount++;
InstanceGblSecIncrLong (&AccountingPtr->CurrentThrottleProcessing);
}
else
{
/********/
/* busy */
/********/
REQUEST_RESET_THROTTLE(rqptr)
tsptr->Total503Count++;
rqptr->rqResponse.HttpStatus = 503;
ErrorGeneral (rqptr, MsgFor(rqptr,MSG_GENERAL_TOO_BUSY), FI_LI);
/* declare an AST to run-down the request */
SysDclAst (&RequestEnd, rqptr);
}
/* reinitialize the timer for output */
HttpdTimerSet (rqptr, TIMER_OUTPUT, 0);
/* indicate it's no longer queued */
rqptr->ThrottleListEntry.DataPtr = NULL;
}
/*****************************************************************************/
/*
Scan through all throttle structures looking for those with queued requests.
Either release all the queued requests for processing, or just release the one
with the specified connect number. This "release" is completely unconditional.
That is a non-extreme-prejudice release sets requests processing regardless of
any processing limitations in the throttle rules!! Return the number of
dequeued requests.
*/
int ThrottleControl
(
BOOL WithExtremePrejudice,
int ConnectNumber,
char *RemoteUser,
char *ScriptName
)
{
int idx, status,
DequeuedCount;
LIST_ENTRY *leptr;
REQUEST_STRUCT *rqptr;
THROTTLE_STRUCT *tsptr;
/*********/
/* begin */
/*********/
if (WATCH_MODULE(WATCH_MOD_THROTTLE))
WatchThis (WATCHALL, WATCH_MOD_THROTTLE,
"ThrottleControl() !UL !&Z !&Z",
WithExtremePrejudice, RemoteUser, ScriptName);
DequeuedCount = 0;
for (idx = 0; idx < MappingMetaPtr->ThrottleTotal; idx++)
{
tsptr = &ThrottleArray[idx];
if (!tsptr->CurrentQueuedCount) continue;
/* scan through all entries on this list */
leptr = tsptr->QueuedList.HeadPtr;
while (leptr)
{
rqptr = (REQUEST_STRUCT*)leptr->DataPtr;
/* IMMEDIATELY get a pointer to the next in the list */
leptr = leptr->NextPtr;
/* if we're looking for a particular request and this is not it */
if (ConnectNumber && rqptr->ConnectNumber != ConnectNumber)
continue;
/* if only purging scripts running as a specific VMS user */
if (RemoteUser && RemoteUser[0])
if (!strsame (rqptr->RemoteUser, RemoteUser, -1))
continue;
/* if only purging matching scripts */
if (ScriptName && ScriptName[0])
if (!StringMatch (NULL, rqptr->ScriptName, ScriptName))
continue;
if (WithExtremePrejudice)
ThrottleRelease (rqptr, NULL, false);
else
ThrottleRelease (rqptr, NULL, true);
DequeuedCount++;
/* if dequeuing just the one request then return now */
if (ConnectNumber) return (DequeuedCount);
}
}
if (WATCH_CAT && Watch.Category)
WatchThis (WATCHALL, WATCH_REQUEST, "THROTTLE control !AZed !UL",
WithExtremePrejudice ? "terminat" : "releas", DequeuedCount);
return (DequeuedCount);
}
/*****************************************************************************/
/*
Provide a report on the current state and history of any throttled paths.
*/
ThrottleReport (REQUEST_STRUCT *rqptr)
{
static char BeginPage [] =
"<p><table class=\"lftlft\">\n\
<tr><th colspan=\"6\"></th>\
<th colspan=\"6\" style=\"vertical-align:bottom;\">Queued</th>\
<th> <th>\
<th colspan=\"2\" style=\"vertical-align:bottom;\">Processing</th>\
<th> <th>\
<th colspan=\"2\" style=\"vertical-align:bottom;\">Per-User</th>\
</tr>\
<tr>\
<th></th>\
<th class=\"sbttl\">Path / User</th>\
<th class=\"sbttl\">Total</th>\
<th class=\"sbttl\">Busy</th>\
<th> <th>\
<th class=\"sbttl\">Total</th>\
<th class=\"sbttl\">Cur</th>\
<th class=\"sbttl\">Max</th>\
<th class=\"sbttl\">FIFO</th>\
<th class=\"sbttl\">T/Oq</th>\
<th class=\"sbttl\">T/Ob</th>\
<th> <th>\
<th class=\"sbttl\">Cur</th>\
<th class=\"sbttl\">Max</th>\
<th> <th>\
<th class=\"sbttl\">Cur</th>\
<th class=\"sbttl\">Max</th>\
<th> </th>\
</tr>\n";
static char ThrottlePathFao [] =
"<tr><th>!3ZL</th>\
<td>!AZ\
throttle=!UL!&@,!UL,!UL,!UL,!AZ,!AZ</td>\
<td>!&L</td>\
<td>!&L</td>\
<td> <td>\
<td>!&L</td>\
<td>!&L</td>\
<td>!&L</td>\
<td>!&L</td>\
<td>!&L</td>\
<td>!&L</td>\
<td> <td>\
<td>!&L</td>\
<td>!&L</td>\
<td> <td>\
<td>!&L</td>\
<td>!&L</td>\
</tr>\n\
<tr class=\"hlght talft\">\
<th></th>\
<td colspan=\"2\"></td>\
<td>!UL%</td>\
<td colspan=\"2\"></td>\
<td>!UL%</td>\
<td colspan=\"2\"></td>\
<td>!UL%</td>\
<td>!UL%</td>\
<td>!UL%</td>\
<td colspan=\"8\" ></td>\
</tr>\n";
static char ThrottleBeginPerUserFao [] =
"<tr><th></th><td colspan=\"13\">";
static char ThrottlePerUserFao [] =
"<span style=\"background:#e5e5e5\">!AZ !UL,!UL,!UL</span> \n";
static char ThrottleEndPerUserFao [] = "</td></tr>\n";
static char ButtonsFao [] =
"</table>\n\
<div style=\"padding-left:0.7em;font-size:90%;font-style:italic;\">\n\
<sup>*</sup>throttle=n1[/u1],n2,n3,n4,to1,to2\n\
<div style=\"padding-left:0.7em;font-size:90%;\">\n\
n1, concurrent requests before queuing\n\
<br>u1, per-user concurrent requests before queuing\n\
<br>n2, concurrent requests before FIFO processing\n\
<br>n3, concurrent requests before FIFO processing ceases again\n\
<br>n4, concurrent requests before immediate "busy"\n\
<br>to1, maximum period queued before processing \
(if not limited by n3)\n\
<br>to2, maximum period queued before "busy" \
(from expiry of any to1)\n\
</div>\n\
<i><sup>**</sup>all percentages are of path total</i>\n\
<br><i><sup>***</sup>user data is queued, processing, total</i>\n\
</div>\n\
<table class=\"lftlft\">\n\
<tr><td>\n\
<form method=\"GET\" action=\"!AZ\">\n\
<input type=\"submit\" value=\"Zero\">\n\
</form>\n\
</td><td>\n\
<form method=\"GET\" action=\"!AZ\">\n\
<input type=\"submit\" value=\"Release\">\n\
</form>\n\
</td><td>\n\
<form method=\"GET\" action=\"!AZ\">\n\
<input type=\"submit\" value=\"Terminate\">\n\
</form>\n\
</td></tr>\n\
<tr><td>\n\
<br><a class=\"abttn bttn600\" href=\"!AZ\">Requests</a>\n\
</td></tr>\n\
</table>\n\
!AZ\
</div>\n\
</body>\n\
</html>\n";
int idx, status;
unsigned long *vecptr;
unsigned long FaoVector [32];
MAP_RULE_META EmptyRuleJustInCase;
MAP_RULE_META *mrptr;
THROTTLE_STRUCT *tsptr;
THROTTLE_PER_USER_STRUCT *tpuptr;
/*********/
/* begin */
/*********/
if (WATCHMOD (rqptr, WATCH_MOD_THROTTLE))
WatchThis (WATCHITM(rqptr), WATCH_MOD_THROTTLE,
"ThrottleReport() !UL", MappingMetaPtr->ThrottleTotal);
AdminPageTitle (rqptr, "Throttle Report", BeginPage);
for (idx = 0; idx < MappingMetaPtr->ThrottleTotal; idx++)
{
tsptr = &ThrottleArray[idx];
/* get details of the throttle rule using the index number */
if (!(mrptr = MapUrl_ThrottleRule (idx)))
{
memset (mrptr = &EmptyRuleJustInCase, 0, sizeof(MAP_RULE_META));
EmptyRuleJustInCase.TemplatePtr = "?";
}
vecptr = FaoVector;
*vecptr++ = idx + 1;
*vecptr++ = mrptr->TemplatePtr;
*vecptr++ = mrptr->mpPathSet.ThrottleFrom;
if (mrptr->mpPathSet.ThrottlePerUser)
{
*vecptr++ = "/!UL";
*vecptr++ = mrptr->mpPathSet.ThrottlePerUser;
}
else
*vecptr++ = "";
*vecptr++ = mrptr->mpPathSet.ThrottleTo;
*vecptr++ = mrptr->mpPathSet.ThrottleResume;
*vecptr++ = mrptr->mpPathSet.ThrottleBusy;
*vecptr++ = MetaConShowSeconds (rqptr,
mrptr->mpPathSet.ThrottleTimeoutQueue);
*vecptr++ = MetaConShowSeconds (rqptr,
mrptr->mpPathSet.ThrottleTimeoutBusy);
*vecptr++ = tsptr->TotalCount;
*vecptr++ = tsptr->Total503Count;
*vecptr++ = tsptr->TotalQueuedCount;
*vecptr++ = tsptr->CurrentQueuedCount;
*vecptr++ = tsptr->MaxQueuedCount;
*vecptr++ = tsptr->TotalFiFoCount;
*vecptr++ = tsptr->TotalTimeoutQueueCount;
*vecptr++ = tsptr->TotalTimeoutBusyCount;
*vecptr++ = tsptr->CurrentProcessingCount;
*vecptr++ = tsptr->MaxProcessingCount;
*vecptr++ = tsptr->CurrentPerUserCount;
*vecptr++ = tsptr->MaxPerUserCount;
*vecptr++ = PercentOf32(tsptr->Total503Count,tsptr->TotalCount);
*vecptr++ = PercentOf32(tsptr->TotalQueuedCount,tsptr->TotalCount);
*vecptr++ = PercentOf32(tsptr->TotalFiFoCount,tsptr->TotalCount);
*vecptr++ = PercentOf32(tsptr->TotalTimeoutQueueCount,tsptr->TotalCount);
*vecptr++ = PercentOf32(tsptr->TotalTimeoutBusyCount,tsptr->TotalCount);
FaoCheck (sizeof(FaoVector), &FaoVector, vecptr, FI_LI);
status = FaolToNet (rqptr, ThrottlePathFao, &FaoVector);
if (VMSnok (status))
ErrorNoticed (rqptr, status, NULL, FI_LI);
/* next throttle entry if there is no per-user list associated */
if (!tsptr->FirstUserPtr) continue;
FaolToNet (rqptr, ThrottleBeginPerUserFao, NULL);
tpuptr = tsptr->FirstUserPtr;
while (tpuptr)
{
vecptr = FaoVector;
*vecptr++ = tpuptr->RemoteUser;
*vecptr++ = tpuptr->CurrentQueuedCount;
*vecptr++ = tpuptr->CurrentProcessingCount;
*vecptr++ = tpuptr->TotalCount;
FaoCheck (sizeof(FaoVector), &FaoVector, vecptr, FI_LI);
status = FaolToNet (rqptr, ThrottlePerUserFao, &FaoVector);
if (VMSnok (status))
ErrorNoticed (rqptr, status, NULL, FI_LI);
tpuptr = tpuptr->NextUserPtr;
}
FaolToNet (rqptr, ThrottleEndPerUserFao, NULL);
}
if (!idx)
FaoToNet (rqptr,
"<tr><td class=\"tacnt\" colspan=\"12\"><i>(none)</i></td></tr>\n",
NULL);
vecptr = FaoVector;
*vecptr++ = ADMIN_CONTROL_THROTTLE_ZERO;
*vecptr++ = ADMIN_CONTROL_THROTTLE_RELEASE;
*vecptr++ = ADMIN_CONTROL_THROTTLE_TERMINATE;
*vecptr++ = ADMIN_REPORT_REQUEST_THROTTLE;
*vecptr++ = AdminRefresh();
FaoCheck (sizeof(FaoVector), &FaoVector, vecptr, FI_LI);
status = FaolToNet (rqptr, ButtonsFao, &FaoVector);
if (VMSnok (status)) ErrorNoticed (rqptr, status, NULL, FI_LI);
rqptr->rqResponse.PreExpired = PRE_EXPIRE_ADMIN;
ResponseHeader200 (rqptr, "text/html", &rqptr->NetWriteBufferDsc);
AdminEnd (rqptr);
}
/*****************************************************************************/