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1 /*
2  *
3  * Copyright 2016 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #include <grpc/support/port_platform.h>
20 
21 #include "src/core/lib/iomgr/port.h"
22 
23 #ifdef GRPC_POSIX_WAKEUP_FD
24 
25 #include "src/core/lib/iomgr/wakeup_fd_cv.h"
26 
27 #include <errno.h>
28 #include <string.h>
29 
30 #include <grpc/support/alloc.h>
31 #include <grpc/support/log.h>
32 #include <grpc/support/sync.h>
33 #include <grpc/support/time.h>
34 
35 #include "src/core/lib/gpr/useful.h"
36 #include "src/core/lib/gprpp/thd.h"
37 
38 #define MAX_TABLE_RESIZE 256
39 
40 extern grpc_cv_fd_table g_cvfds;
41 
cv_fd_init(grpc_wakeup_fd * fd_info)42 static grpc_error* cv_fd_init(grpc_wakeup_fd* fd_info) {
43   unsigned int i, newsize;
44   int idx;
45   gpr_mu_lock(&g_cvfds.mu);
46   if (!g_cvfds.free_fds) {
47     newsize = GPR_MIN(g_cvfds.size * 2, g_cvfds.size + MAX_TABLE_RESIZE);
48     g_cvfds.cvfds = static_cast<grpc_fd_node*>(
49         gpr_realloc(g_cvfds.cvfds, sizeof(grpc_fd_node) * newsize));
50     for (i = g_cvfds.size; i < newsize; i++) {
51       g_cvfds.cvfds[i].is_set = 0;
52       g_cvfds.cvfds[i].cvs = nullptr;
53       g_cvfds.cvfds[i].next_free = g_cvfds.free_fds;
54       g_cvfds.free_fds = &g_cvfds.cvfds[i];
55     }
56     g_cvfds.size = newsize;
57   }
58 
59   idx = static_cast<int>(g_cvfds.free_fds - g_cvfds.cvfds);
60   g_cvfds.free_fds = g_cvfds.free_fds->next_free;
61   g_cvfds.cvfds[idx].cvs = nullptr;
62   g_cvfds.cvfds[idx].is_set = 0;
63   fd_info->read_fd = GRPC_IDX_TO_FD(idx);
64   fd_info->write_fd = -1;
65   gpr_mu_unlock(&g_cvfds.mu);
66   return GRPC_ERROR_NONE;
67 }
68 
cv_fd_wakeup(grpc_wakeup_fd * fd_info)69 static grpc_error* cv_fd_wakeup(grpc_wakeup_fd* fd_info) {
70   grpc_cv_node* cvn;
71   gpr_mu_lock(&g_cvfds.mu);
72   g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].is_set = 1;
73   cvn = g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].cvs;
74   while (cvn) {
75     gpr_cv_signal(cvn->cv);
76     cvn = cvn->next;
77   }
78   gpr_mu_unlock(&g_cvfds.mu);
79   return GRPC_ERROR_NONE;
80 }
81 
cv_fd_consume(grpc_wakeup_fd * fd_info)82 static grpc_error* cv_fd_consume(grpc_wakeup_fd* fd_info) {
83   gpr_mu_lock(&g_cvfds.mu);
84   g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].is_set = 0;
85   gpr_mu_unlock(&g_cvfds.mu);
86   return GRPC_ERROR_NONE;
87 }
88 
cv_fd_destroy(grpc_wakeup_fd * fd_info)89 static void cv_fd_destroy(grpc_wakeup_fd* fd_info) {
90   if (fd_info->read_fd == 0) {
91     return;
92   }
93   gpr_mu_lock(&g_cvfds.mu);
94   // Assert that there are no active pollers
95   GPR_ASSERT(!g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].cvs);
96   g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)].next_free = g_cvfds.free_fds;
97   g_cvfds.free_fds = &g_cvfds.cvfds[GRPC_FD_TO_IDX(fd_info->read_fd)];
98   gpr_mu_unlock(&g_cvfds.mu);
99 }
100 
cv_check_availability(void)101 static int cv_check_availability(void) { return 1; }
102 
103 const grpc_wakeup_fd_vtable grpc_cv_wakeup_fd_vtable = {
104     cv_fd_init, cv_fd_consume, cv_fd_wakeup, cv_fd_destroy,
105     cv_check_availability};
106 
107 #endif /* GRPC_POSIX_WAKUP_FD */
108