summaryrefslogtreecommitdiff
path: root/indra/llcorehttp/_httppolicy.cpp
blob: 704c8abb937e5daa5a423aa740732013b385d2b2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
/**
 * @file _httppolicy.cpp
 * @brief Internal definitions of the Http policy thread
 *
 * $LicenseInfo:firstyear=2012&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2012-2014, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "linden_common.h"

#include "_httppolicy.h"

#include "_httpoprequest.h"
#include "_httpservice.h"
#include "_httplibcurl.h"
#include "_httppolicyclass.h"

#include "lltimer.h"
#include "httpstats.h"

namespace
{

static const char * const LOG_CORE("CoreHttp");

} // end anonymous namespace


namespace LLCore
{


// Per-policy-class data for a running system.
// Collection of queues, options and other data
// for a single policy class.
//
// Threading:  accessed only by worker thread
struct HttpPolicy::ClassState
{
public:
    ClassState()
        : mThrottleEnd(0),
          mThrottleLeft(0L),
          mRequestCount(0L),
          mStallStaging(false)
        {}

    HttpReadyQueue      mReadyQueue;
    HttpRetryQueue      mRetryQueue;

    HttpPolicyClass     mOptions;
    HttpTime            mThrottleEnd;
    long                mThrottleLeft;
    long                mRequestCount;
    bool                mStallStaging;
};


HttpPolicy::HttpPolicy(HttpService * service)
    : mService(service)
{
    // Create default class
    mClasses.push_back(new ClassState());
}


HttpPolicy::~HttpPolicy()
{
    shutdown();

    for (class_list_t::iterator it(mClasses.begin()); it != mClasses.end(); ++it)
    {
        delete (*it);
    }
    mClasses.clear();

    mService = NULL;
}


HttpRequest::policy_t HttpPolicy::createPolicyClass()
{
    const HttpRequest::policy_t policy_class(mClasses.size());
    if (policy_class >= HTTP_POLICY_CLASS_LIMIT)
    {
        return HttpRequest::INVALID_POLICY_ID;
    }
    mClasses.push_back(new ClassState());
    return policy_class;
}


void HttpPolicy::shutdown()
{
    for (int policy_class(0); policy_class < mClasses.size(); ++policy_class)
    {
        ClassState & state(*mClasses[policy_class]);

        HttpRetryQueue & retryq(state.mRetryQueue);
        while (! retryq.empty())
        {
            HttpOpRequest::ptr_t op(retryq.top());
            retryq.pop();

            op->cancel();
        }

        HttpReadyQueue & readyq(state.mReadyQueue);
        while (! readyq.empty())
        {
            HttpOpRequest::ptr_t op(readyq.top());
            readyq.pop();

            op->cancel();
        }
    }
}


void HttpPolicy::start()
{
}


void HttpPolicy::addOp(const HttpOpRequest::ptr_t &op)
{
    const int policy_class(op->mReqPolicy);

    op->mPolicyRetries = 0;
    op->mPolicy503Retries = 0;
    mClasses[policy_class]->mReadyQueue.push(op);
}


void HttpPolicy::retryOp(const HttpOpRequest::ptr_t &op)
{
    static const HttpStatus error_503(503);

    const HttpTime now(totalTime());
    const int policy_class(op->mReqPolicy);

    HttpTime delta_min = op->mPolicyMinRetryBackoff;
    HttpTime delta_max = op->mPolicyMaxRetryBackoff;
    // mPolicyRetries limited to 100
    U32 delta_factor = op->mPolicyRetries <= 10 ? 1 << op->mPolicyRetries : 1024;
    HttpTime delta = llmin(delta_min * delta_factor, delta_max);
    bool external_delta(false);

    if (op->mReplyRetryAfter > 0 && op->mReplyRetryAfter < 30)
    {
        delta = op->mReplyRetryAfter * U64L(1000000);
        external_delta = true;
    }
    op->mPolicyRetryAt = now + delta;
    ++op->mPolicyRetries;
    if (error_503 == op->mStatus)
    {
        ++op->mPolicy503Retries;
    }
    LL_DEBUGS(LOG_CORE) << "HTTP request " << op->getHandle()
                        << " retry " << op->mPolicyRetries
                        << " scheduled in " << (delta / HttpTime(1000))
                        << " mS (" << (external_delta ? "external" : "internal")
                        << ").  Status:  " << op->mStatus.toTerseString()
                        << LL_ENDL;
    if (op->mTracing > HTTP_TRACE_OFF)
    {
        LL_INFOS(LOG_CORE) << "TRACE, ToRetryQueue, Handle:  "
                            << op->getHandle()
                            << ", Delta:  " << (delta / HttpTime(1000))
                            << ", Retries:  " << op->mPolicyRetries
                            << LL_ENDL;
    }
    mClasses[policy_class]->mRetryQueue.push(op);
}


// Attempt to deliver requests to the transport layer.
//
// Tries to find HTTP requests for each policy class with
// available capacity.  Starts with the retry queue first
// looking for requests that have waited long enough then
// moves on to the ready queue.
//
// If all queues are empty, will return an indication that
// the worker thread may sleep hard otherwise will ask for
// normal polling frequency.
//
// Implements a client-side request rate throttle as well.
// This is intended to mimic and predict throttling behavior
// of grid services but that is difficult to do with different
// time bases.  This also represents a rigid coupling between
// viewer and server that makes it hard to change parameters
// and I hope we can make this go away with pipelining.
//
HttpService::ELoopSpeed HttpPolicy::processReadyQueue()
{
    const HttpTime now(totalTime());
    HttpService::ELoopSpeed result(HttpService::REQUEST_SLEEP);
    HttpLibcurl & transport(mService->getTransport());

    for (int policy_class(0); policy_class < mClasses.size(); ++policy_class)
    {
        ClassState & state(*mClasses[policy_class]);
        HttpRetryQueue & retryq(state.mRetryQueue);
        HttpReadyQueue & readyq(state.mReadyQueue);

        if (state.mStallStaging)
        {
            // Stalling but don't sleep.  Need to complete operations
            // and get back to servicing queues.  Do this test before
            // the retryq/readyq test or you'll get stalls until you
            // click a setting or an asset request comes in.
            result = HttpService::NORMAL;
            continue;
        }
        if (retryq.empty() && readyq.empty())
        {
            continue;
        }

        const bool throttle_enabled(state.mOptions.mThrottleRate > 0L);
        const bool throttle_current(throttle_enabled && now < state.mThrottleEnd);

        if (throttle_current && state.mThrottleLeft <= 0)
        {
            // Throttled condition, don't serve this class but don't sleep hard.
            result = HttpService::NORMAL;
            continue;
        }

        int active(transport.getActiveCountInClass(policy_class));
        int active_limit(state.mOptions.mPipelining > 1L
                         ? (state.mOptions.mPerHostConnectionLimit
                            * state.mOptions.mPipelining)
                         : state.mOptions.mConnectionLimit);
        int needed(active_limit - active);      // Expect negatives here

        if (needed > 0)
        {
            // First see if we have any retries...
            while (needed > 0 && ! retryq.empty())
            {
                HttpOpRequest::ptr_t op(retryq.top());
                if (op->mPolicyRetryAt > now)
                    break;

                retryq.pop();

                op->stageFromReady(mService);
                op.reset();

                ++state.mRequestCount;
                --needed;
                if (throttle_enabled)
                {
                    if (now >= state.mThrottleEnd)
                    {
                        // Throttle expired, move to next window
                        LL_DEBUGS(LOG_CORE) << "Throttle expired with " << state.mThrottleLeft
                                            << " requests to go and " << state.mRequestCount
                                            << " requests issued." << LL_ENDL;
                        state.mThrottleLeft = state.mOptions.mThrottleRate;
                        state.mThrottleEnd = now + HttpTime(1000000);
                    }
                    if (--state.mThrottleLeft <= 0)
                    {
                        goto throttle_on;
                    }
                }
            }

            // Now go on to the new requests...
            while (needed > 0 && ! readyq.empty())
            {
                HttpOpRequest::ptr_t op(readyq.top());
                readyq.pop();

                op->stageFromReady(mService);
                op.reset();

                ++state.mRequestCount;
                --needed;
                if (throttle_enabled)
                {
                    if (now >= state.mThrottleEnd)
                    {
                        // Throttle expired, move to next window
                        LL_DEBUGS(LOG_CORE) << "Throttle expired with " << state.mThrottleLeft
                                            << " requests to go and " << state.mRequestCount
                                            << " requests issued." << LL_ENDL;
                        state.mThrottleLeft = state.mOptions.mThrottleRate;
                        state.mThrottleEnd = now + HttpTime(1000000);
                    }
                    if (--state.mThrottleLeft <= 0)
                    {
                        goto throttle_on;
                    }
                }
            }
        }

    throttle_on:

        if (! readyq.empty() || ! retryq.empty())
        {
            // If anything is ready, continue looping...
            result = HttpService::NORMAL;
        }
    } // end foreach policy_class

    return result;
}

bool HttpPolicy::cancel(HttpHandle handle)
{
    for (int policy_class(0); policy_class < mClasses.size(); ++policy_class)
    {
        ClassState & state(*mClasses[policy_class]);

        // Scan retry queue
        HttpRetryQueue::container_type & c1(state.mRetryQueue.get_container());
        for (HttpRetryQueue::container_type::iterator iter(c1.begin()); c1.end() != iter;)
        {
            HttpRetryQueue::container_type::iterator cur(iter++);

            if ((*cur)->getHandle() == handle)
            {
                HttpOpRequest::ptr_t op(*cur);
                c1.erase(cur);                                  // All iterators are now invalidated
                op->cancel();
                return true;
            }
        }

        // Scan ready queue
        HttpReadyQueue::container_type & c2(state.mReadyQueue.get_container());
        for (HttpReadyQueue::container_type::iterator iter(c2.begin()); c2.end() != iter;)
        {
            HttpReadyQueue::container_type::iterator cur(iter++);

            if ((*cur)->getHandle() == handle)
            {
                HttpOpRequest::ptr_t op(*cur);
                c2.erase(cur);                                  // All iterators are now invalidated
                op->cancel();
                return true;
            }
        }
    }

    return false;
}


bool HttpPolicy::stageAfterCompletion(const HttpOpRequest::ptr_t &op)
{
    // Retry or finalize
    if (! op->mStatus)
    {
        // *DEBUG:  For "[curl:bugs] #1420" tests.  This will interfere
        // with unit tests due to allocation retention by logging code.
        // But you won't be checking this in enabled.
#if 0
        if (op->mStatus == HttpStatus(HttpStatus::EXT_CURL_EASY, CURLE_OPERATION_TIMEDOUT))
        {
            LL_WARNS(LOG_CORE) << "HTTP request " << op->getHandle()
                               << " timed out."
                               << LL_ENDL;
        }
#endif

        // If this failed, we might want to retry.
        if (op->mPolicyRetries < op->mPolicyRetryLimit && op->mStatus.isRetryable())
        {
            // Okay, worth a retry.
            retryOp(op);
            return true;                // still active/ready
        }
    }

    // This op is done, finalize it delivering it to the reply queue...
    if (! op->mStatus)
    {
        LL_WARNS(LOG_CORE) << "HTTP request " << op->getHandle()
                           << " failed after " << op->mPolicyRetries
                           << " retries.  Reason:  " << op->mStatus.toString()
                           << " (" << op->mStatus.toTerseString() << ")"
                           << LL_ENDL;
    }
    else if (op->mPolicyRetries)
    {
        LL_DEBUGS(LOG_CORE) << "HTTP request " << op->getHandle()
                            << " succeeded on retry " << op->mPolicyRetries << "."
                            << LL_ENDL;
    }

    op->stageFromActive(mService);

    HTTPStats::instance().recordResultCode(op->mStatus.getType());
    return false;                       // not active
}


HttpPolicyClass & HttpPolicy::getClassOptions(HttpRequest::policy_t pclass)
{
    llassert_always(pclass >= 0 && pclass < mClasses.size());

    return mClasses[pclass]->mOptions;
}


int HttpPolicy::getReadyCount(HttpRequest::policy_t policy_class) const
{
    if (policy_class < mClasses.size())
    {
        return (mClasses[policy_class]->mReadyQueue.size()
                + mClasses[policy_class]->mRetryQueue.size());
    }
    return 0;
}


bool HttpPolicy::stallPolicy(HttpRequest::policy_t policy_class, bool stall)
{
    bool ret(false);

    if (policy_class < mClasses.size())
    {
        ret = mClasses[policy_class]->mStallStaging;
        mClasses[policy_class]->mStallStaging = stall;
    }
    return ret;
}


}  // end namespace LLCore