aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/core/ext/resolver/zookeeper/zookeeper_resolver.c
blob: 5acb0940c6ff9b7c5f9ae6c9e4cdfdee78d6ea04 (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
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <string.h>

#include <grpc/support/alloc.h>
#include <grpc/support/string_util.h>

#include <grpc/grpc_zookeeper.h>
#include <zookeeper/zookeeper.h>

#include "src/core/lib/client_config/lb_policy_registry.h"
#include "src/core/lib/client_config/resolver_registry.h"
#include "src/core/lib/iomgr/resolve_address.h"
#include "src/core/lib/json/json.h"
#include "src/core/lib/support/string.h"
#include "src/core/lib/surface/api_trace.h"

/** Zookeeper session expiration time in milliseconds */
#define GRPC_ZOOKEEPER_SESSION_TIMEOUT 15000

typedef struct {
  /** base class: must be first */
  grpc_resolver base;
  /** refcount */
  gpr_refcount refs;
  /** name to resolve */
  char *name;
  /** subchannel factory */
  grpc_subchannel_factory *subchannel_factory;
  /** load balancing policy name */
  char *lb_policy_name;

  /** mutex guarding the rest of the state */
  gpr_mu mu;
  /** are we currently resolving? */
  int resolving;
  /** which version of resolved_config have we published? */
  int published_version;
  /** which version of resolved_config is current? */
  int resolved_version;
  /** pending next completion, or NULL */
  grpc_closure *next_completion;
  /** target config address for next completion */
  grpc_client_config **target_config;
  /** current (fully resolved) config */
  grpc_client_config *resolved_config;

  /** zookeeper handle */
  zhandle_t *zookeeper_handle;
  /** zookeeper resolved addresses */
  grpc_resolved_addresses *resolved_addrs;
  /** total number of addresses to be resolved */
  int resolved_total;
  /** number of addresses resolved */
  int resolved_num;
} zookeeper_resolver;

static void zookeeper_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *r);

static void zookeeper_start_resolving_locked(zookeeper_resolver *r);
static void zookeeper_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
                                               zookeeper_resolver *r);

static void zookeeper_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
static void zookeeper_channel_saw_error(grpc_exec_ctx *exec_ctx,
                                        grpc_resolver *r);
static void zookeeper_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r,
                           grpc_client_config **target_config,
                           grpc_closure *on_complete);

static const grpc_resolver_vtable zookeeper_resolver_vtable = {
    zookeeper_destroy, zookeeper_shutdown, zookeeper_channel_saw_error,
    zookeeper_next};

static void zookeeper_shutdown(grpc_exec_ctx *exec_ctx,
                               grpc_resolver *resolver) {
  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
  grpc_closure *call = NULL;
  gpr_mu_lock(&r->mu);
  if (r->next_completion != NULL) {
    *r->target_config = NULL;
    call = r->next_completion;
    r->next_completion = NULL;
  }
  zookeeper_close(r->zookeeper_handle);
  gpr_mu_unlock(&r->mu);
  if (call != NULL) {
    call->cb(exec_ctx, call->cb_arg, 1);
  }
}

static void zookeeper_channel_saw_error(grpc_exec_ctx *exec_ctx,
                                        grpc_resolver *resolver) {
  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
  gpr_mu_lock(&r->mu);
  if (r->resolving == 0) {
    zookeeper_start_resolving_locked(r);
  }
  gpr_mu_unlock(&r->mu);
}

static void zookeeper_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
                           grpc_client_config **target_config,
                           grpc_closure *on_complete) {
  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
  gpr_mu_lock(&r->mu);
  GPR_ASSERT(r->next_completion == NULL);
  r->next_completion = on_complete;
  r->target_config = target_config;
  if (r->resolved_version == 0 && r->resolving == 0) {
    zookeeper_start_resolving_locked(r);
  } else {
    zookeeper_maybe_finish_next_locked(exec_ctx, r);
  }
  gpr_mu_unlock(&r->mu);
}

/** Zookeeper global watcher for connection management
    TODO: better connection management besides logs */
static void zookeeper_global_watcher(zhandle_t *zookeeper_handle, int type,
                                     int state, const char *path,
                                     void *watcher_ctx) {
  if (type == ZOO_SESSION_EVENT) {
    if (state == ZOO_EXPIRED_SESSION_STATE) {
      gpr_log(GPR_ERROR, "Zookeeper session expired");
    } else if (state == ZOO_AUTH_FAILED_STATE) {
      gpr_log(GPR_ERROR, "Zookeeper authentication failed");
    }
  }
}

/** Zookeeper watcher triggered by changes to watched nodes
    Once triggered, it tries to resolve again to get updated addresses */
static void zookeeper_watcher(zhandle_t *zookeeper_handle, int type, int state,
                              const char *path, void *watcher_ctx) {
  if (watcher_ctx != NULL) {
    zookeeper_resolver *r = (zookeeper_resolver *)watcher_ctx;
    if (state == ZOO_CONNECTED_STATE) {
      gpr_mu_lock(&r->mu);
      if (r->resolving == 0) {
        zookeeper_start_resolving_locked(r);
      }
      gpr_mu_unlock(&r->mu);
    }
  }
}

/** Callback function after getting all resolved addresses
    Creates a subchannel for each address */
static void zookeeper_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
                                  grpc_resolved_addresses *addresses) {
  zookeeper_resolver *r = arg;
  grpc_client_config *config = NULL;
  grpc_lb_policy *lb_policy;

  if (addresses != NULL) {
    grpc_lb_policy_args lb_policy_args;
    config = grpc_client_config_create();

    lb_policy_args.addresses = addresses;
    lb_policy_args.subchannel_factory = r->subchannel_factory;
    lb_policy =
        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);

    if (lb_policy != NULL) {
      grpc_client_config_set_lb_policy(config, lb_policy);
      GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
    }
    grpc_resolved_addresses_destroy(addresses);
  }
  gpr_mu_lock(&r->mu);
  GPR_ASSERT(r->resolving == 1);
  r->resolving = 0;
  if (r->resolved_config != NULL) {
    grpc_client_config_unref(exec_ctx, r->resolved_config);
  }
  r->resolved_config = config;
  r->resolved_version++;
  zookeeper_maybe_finish_next_locked(exec_ctx, r);
  gpr_mu_unlock(&r->mu);

  GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "zookeeper-resolving");
}

/** Callback function for each DNS resolved address */
static void zookeeper_dns_resolved(grpc_exec_ctx *exec_ctx, void *arg,
                                   grpc_resolved_addresses *addresses) {
  size_t i;
  zookeeper_resolver *r = arg;
  int resolve_done = 0;

  gpr_mu_lock(&r->mu);
  r->resolved_num++;
  r->resolved_addrs->addrs =
      gpr_realloc(r->resolved_addrs->addrs,
                  sizeof(grpc_resolved_address) *
                      (r->resolved_addrs->naddrs + addresses->naddrs));
  for (i = 0; i < addresses->naddrs; i++) {
    memcpy(r->resolved_addrs->addrs[i + r->resolved_addrs->naddrs].addr,
           addresses->addrs[i].addr, addresses->addrs[i].len);
    r->resolved_addrs->addrs[i + r->resolved_addrs->naddrs].len =
        addresses->addrs[i].len;
  }

  r->resolved_addrs->naddrs += addresses->naddrs;
  grpc_resolved_addresses_destroy(addresses);

  /** Wait for all addresses to be resolved */
  resolve_done = (r->resolved_num == r->resolved_total);
  gpr_mu_unlock(&r->mu);
  if (resolve_done) {
    zookeeper_on_resolved(exec_ctx, r, r->resolved_addrs);
  }
}

/** Parses JSON format address of a zookeeper node */
static char *zookeeper_parse_address(const char *value, size_t value_len) {
  grpc_json *json;
  grpc_json *cur;
  const char *host;
  const char *port;
  char *buffer;
  char *address = NULL;

  buffer = gpr_malloc(value_len);
  memcpy(buffer, value, value_len);
  json = grpc_json_parse_string_with_len(buffer, value_len);
  if (json != NULL) {
    host = NULL;
    port = NULL;
    for (cur = json->child; cur != NULL; cur = cur->next) {
      if (!strcmp(cur->key, "host")) {
        host = cur->value;
        if (port != NULL) {
          break;
        }
      } else if (!strcmp(cur->key, "port")) {
        port = cur->value;
        if (host != NULL) {
          break;
        }
      }
    }
    if (host != NULL && port != NULL) {
      gpr_asprintf(&address, "%s:%s", host, port);
    }
    grpc_json_destroy(json);
  }
  gpr_free(buffer);

  return address;
}

static void zookeeper_get_children_node_completion(int rc, const char *value,
                                                   int value_len,
                                                   const struct Stat *stat,
                                                   const void *arg) {
  char *address = NULL;
  zookeeper_resolver *r = (zookeeper_resolver *)arg;
  int resolve_done = 0;
  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;

  if (rc != 0) {
    gpr_log(GPR_ERROR, "Error in getting a child node of %s", r->name);
    grpc_exec_ctx_finish(&exec_ctx);
    return;
  }

  address = zookeeper_parse_address(value, (size_t)value_len);
  if (address != NULL) {
    /** Further resolves address by DNS */
    grpc_resolve_address(address, NULL, zookeeper_dns_resolved, r);
    gpr_free(address);
  } else {
    gpr_log(GPR_ERROR, "Error in resolving a child node of %s", r->name);
    gpr_mu_lock(&r->mu);
    r->resolved_total--;
    resolve_done = (r->resolved_num == r->resolved_total);
    gpr_mu_unlock(&r->mu);
    if (resolve_done) {
      zookeeper_on_resolved(&exec_ctx, r, r->resolved_addrs);
    }
  }

  grpc_exec_ctx_finish(&exec_ctx);
}

static void zookeeper_get_children_completion(
    int rc, const struct String_vector *children, const void *arg) {
  char *path;
  int status;
  int i;
  zookeeper_resolver *r = (zookeeper_resolver *)arg;

  if (rc != 0) {
    gpr_log(GPR_ERROR, "Error in getting zookeeper children of %s", r->name);
    return;
  }

  if (children->count == 0) {
    gpr_log(GPR_ERROR, "Error in resolving zookeeper address %s", r->name);
    return;
  }

  r->resolved_addrs = gpr_malloc(sizeof(grpc_resolved_addresses));
  r->resolved_addrs->addrs = NULL;
  r->resolved_addrs->naddrs = 0;
  r->resolved_total = children->count;

  /** TODO: Replace expensive heap allocation with stack
      if we can get maximum length of zookeeper path */
  for (i = 0; i < children->count; i++) {
    gpr_asprintf(&path, "%s/%s", r->name, children->data[i]);
    status = zoo_awget(r->zookeeper_handle, path, zookeeper_watcher, r,
                       zookeeper_get_children_node_completion, r);
    gpr_free(path);
    if (status != 0) {
      gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", path);
    }
  }
}

static void zookeeper_get_node_completion(int rc, const char *value,
                                          int value_len,
                                          const struct Stat *stat,
                                          const void *arg) {
  int status;
  char *address = NULL;
  zookeeper_resolver *r = (zookeeper_resolver *)arg;
  r->resolved_addrs = NULL;
  r->resolved_total = 0;
  r->resolved_num = 0;

  if (rc != 0) {
    gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", r->name);
    return;
  }

  /** If zookeeper node of path r->name does not have address
      (i.e. service node), get its children */
  address = zookeeper_parse_address(value, (size_t)value_len);
  if (address != NULL) {
    r->resolved_addrs = gpr_malloc(sizeof(grpc_resolved_addresses));
    r->resolved_addrs->addrs = NULL;
    r->resolved_addrs->naddrs = 0;
    r->resolved_total = 1;
    /** Further resolves address by DNS */
    grpc_resolve_address(address, NULL, zookeeper_dns_resolved, r);
    gpr_free(address);
    return;
  }

  status = zoo_awget_children(r->zookeeper_handle, r->name, zookeeper_watcher,
                              r, zookeeper_get_children_completion, r);
  if (status != 0) {
    gpr_log(GPR_ERROR, "Error in getting zookeeper children of %s", r->name);
  }
}

static void zookeeper_resolve_address(zookeeper_resolver *r) {
  int status;
  status = zoo_awget(r->zookeeper_handle, r->name, zookeeper_watcher, r,
                     zookeeper_get_node_completion, r);
  if (status != 0) {
    gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", r->name);
  }
}

static void zookeeper_start_resolving_locked(zookeeper_resolver *r) {
  GRPC_RESOLVER_REF(&r->base, "zookeeper-resolving");
  GPR_ASSERT(r->resolving == 0);
  r->resolving = 1;
  zookeeper_resolve_address(r);
}

static void zookeeper_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
                                               zookeeper_resolver *r) {
  if (r->next_completion != NULL &&
      r->resolved_version != r->published_version) {
    *r->target_config = r->resolved_config;
    if (r->resolved_config != NULL) {
      grpc_client_config_ref(r->resolved_config);
    }
    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
    r->next_completion = NULL;
    r->published_version = r->resolved_version;
  }
}

static void zookeeper_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
  zookeeper_resolver *r = (zookeeper_resolver *)gr;
  gpr_mu_destroy(&r->mu);
  if (r->resolved_config != NULL) {
    grpc_client_config_unref(exec_ctx, r->resolved_config);
  }
  grpc_subchannel_factory_unref(exec_ctx, r->subchannel_factory);
  gpr_free(r->name);
  gpr_free(r->lb_policy_name);
  gpr_free(r);
}

static grpc_resolver *zookeeper_create(grpc_resolver_args *args,
                                       const char *lb_policy_name) {
  zookeeper_resolver *r;
  size_t length;
  char *path = args->uri->path;

  if (0 == strcmp(args->uri->authority, "")) {
    gpr_log(GPR_ERROR, "No authority specified in zookeeper uri");
    return NULL;
  }

  /** Removes the trailing slash if exists */
  length = strlen(path);
  if (length > 1 && path[length - 1] == '/') {
    path[length - 1] = 0;
  }

  r = gpr_malloc(sizeof(zookeeper_resolver));
  memset(r, 0, sizeof(*r));
  gpr_ref_init(&r->refs, 1);
  gpr_mu_init(&r->mu);
  grpc_resolver_init(&r->base, &zookeeper_resolver_vtable);
  r->name = gpr_strdup(path);

  r->subchannel_factory = args->subchannel_factory;
  grpc_subchannel_factory_ref(r->subchannel_factory);

  r->lb_policy_name = gpr_strdup(lb_policy_name);

  /** Initializes zookeeper client */
  zoo_set_debug_level(ZOO_LOG_LEVEL_WARN);
  r->zookeeper_handle =
      zookeeper_init(args->uri->authority, zookeeper_global_watcher,
                     GRPC_ZOOKEEPER_SESSION_TIMEOUT, 0, 0, 0);
  if (r->zookeeper_handle == NULL) {
    gpr_log(GPR_ERROR, "Unable to connect to zookeeper server");
    return NULL;
  }

  return &r->base;
}

/*
 * FACTORY
 */

static void zookeeper_factory_ref(grpc_resolver_factory *factory) {}

static void zookeeper_factory_unref(grpc_resolver_factory *factory) {}

static char *zookeeper_factory_get_default_hostname(
    grpc_resolver_factory *factory, grpc_uri *uri) {
  return NULL;
}

static grpc_resolver *zookeeper_factory_create_resolver(
    grpc_resolver_factory *factory, grpc_resolver_args *args) {
  return zookeeper_create(args, "pick_first");
}

static const grpc_resolver_factory_vtable zookeeper_factory_vtable = {
    zookeeper_factory_ref, zookeeper_factory_unref,
    zookeeper_factory_create_resolver, zookeeper_factory_get_default_hostname,
    "zookeeper"};

static grpc_resolver_factory zookeeper_resolver_factory = {
    &zookeeper_factory_vtable};

static grpc_resolver_factory *zookeeper_resolver_factory_create() {
  return &zookeeper_resolver_factory;
}

static void zookeeper_plugin_init() {
  grpc_register_resolver_type(zookeeper_resolver_factory_create());
}

void grpc_zookeeper_register() {
  GRPC_API_TRACE("grpc_zookeeper_register(void)", 0, ());
  grpc_register_plugin(zookeeper_plugin_init, NULL);
}