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authorGergely Nagy <ngg@tresorit.com>2019-11-17 15:12:15 +0100
committerDaniel Stenberg <daniel@haxx.se>2019-11-25 15:45:56 +0100
commitf3c35e371cc70f1b6bc33f7faa904d37d1567eb3 (patch)
tree3c7668dec5726aa510d7be282ff440c9ee370802 /lib
parent0a65febccf0e31bc987be3f90c01194804e61b77 (diff)
downloadcurl-f3c35e371cc70f1b6bc33f7faa904d37d1567eb3.tar.gz
multi: add curl_multi_wakeup()
This commit adds curl_multi_wakeup() which was previously in the TODO list under the curl_multi_unblock name. On some platforms and with some configurations this feature might not be available or can fail, in these cases a new error code (CURLM_WAKEUP_FAILURE) is returned from curl_multi_wakeup(). Fixes #4418 Closes #4608
Diffstat (limited to 'lib')
-rwxr-xr-xlib/multi.c114
-rw-r--r--lib/multihandle.h10
-rw-r--r--lib/strerror.c3
3 files changed, 124 insertions, 3 deletions
diff --git a/lib/multi.c b/lib/multi.c
index 9faad0e2e..f30e41a65 100755
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -46,6 +46,7 @@
#include "connect.h"
#include "http_proxy.h"
#include "http2.h"
+#include "socketpair.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
@@ -367,6 +368,21 @@ struct Curl_multi *Curl_multi_handle(int hashsize, /* socket hash */
/* -1 means it not set by user, use the default value */
multi->maxconnects = -1;
+
+#ifdef ENABLE_WAKEUP
+ if(Curl_socketpair(AF_UNIX, SOCK_STREAM, 0, multi->wakeup_pair) < 0) {
+ multi->wakeup_pair[0] = CURL_SOCKET_BAD;
+ multi->wakeup_pair[1] = CURL_SOCKET_BAD;
+ }
+ else if(curlx_nonblock(multi->wakeup_pair[0], TRUE) < 0 ||
+ curlx_nonblock(multi->wakeup_pair[1], TRUE) < 0) {
+ sclose(multi->wakeup_pair[0]);
+ sclose(multi->wakeup_pair[1]);
+ multi->wakeup_pair[0] = CURL_SOCKET_BAD;
+ multi->wakeup_pair[1] = CURL_SOCKET_BAD;
+ }
+#endif
+
return multi;
error:
@@ -1005,7 +1021,8 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
unsigned int extra_nfds,
int timeout_ms,
int *ret,
- bool extrawait) /* when no socket, wait */
+ bool extrawait, /* when no socket, wait */
+ bool use_wakeup)
{
struct Curl_easy *data;
curl_socket_t sockbunch[MAX_SOCKSPEREASYHANDLE];
@@ -1059,6 +1076,12 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
curlfds = nfds; /* number of internal file descriptors */
nfds += extra_nfds; /* add the externally provided ones */
+#ifdef ENABLE_WAKEUP
+ if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
+ ++nfds;
+ }
+#endif
+
if(nfds > NUM_POLLS_ON_STACK) {
/* 'nfds' is a 32 bit value and 'struct pollfd' is typically 8 bytes
big, so at 2^29 sockets this value might wrap. When a process gets
@@ -1117,6 +1140,14 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
++nfds;
}
+#ifdef ENABLE_WAKEUP
+ if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
+ ufds[nfds].fd = multi->wakeup_pair[0];
+ ufds[nfds].events = POLLIN;
+ ++nfds;
+ }
+#endif
+
if(nfds) {
int pollrc;
/* wait... */
@@ -1140,6 +1171,29 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
extra_fds[i].revents = mask;
}
+
+#ifdef ENABLE_WAKEUP
+ if(use_wakeup && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
+ if(ufds[curlfds + extra_nfds].revents & POLLIN) {
+ char buf[64];
+ while(1) {
+ /* the reading socket is non-blocking, try to read
+ data from it until it receives an error (except EINTR).
+ In normal cases it will get EAGAIN or EWOULDBLOCK
+ when there is no more data, breaking the loop. */
+ if(sread(multi->wakeup_pair[0], buf, sizeof(buf)) < 0) {
+#ifndef USE_WINSOCK
+ if(EINTR == SOCKERRNO)
+ continue;
+#endif
+ break;
+ }
+ }
+ /* do not count the wakeup socket into the returned value */
+ retcode--;
+ }
+ }
+#endif
}
}
@@ -1174,7 +1228,8 @@ CURLMcode curl_multi_wait(struct Curl_multi *multi,
int timeout_ms,
int *ret)
{
- return Curl_multi_wait(multi, extra_fds, extra_nfds, timeout_ms, ret, FALSE);
+ return Curl_multi_wait(multi, extra_fds, extra_nfds, timeout_ms, ret, FALSE,
+ FALSE);
}
CURLMcode curl_multi_poll(struct Curl_multi *multi,
@@ -1183,7 +1238,55 @@ CURLMcode curl_multi_poll(struct Curl_multi *multi,
int timeout_ms,
int *ret)
{
- return Curl_multi_wait(multi, extra_fds, extra_nfds, timeout_ms, ret, TRUE);
+ return Curl_multi_wait(multi, extra_fds, extra_nfds, timeout_ms, ret, TRUE,
+ TRUE);
+}
+
+CURLMcode curl_multi_wakeup(struct Curl_multi *multi)
+{
+ /* this function is usually called from another thread,
+ it has to be careful only to access parts of the
+ Curl_multi struct that are constant */
+
+ /* GOOD_MULTI_HANDLE can be safely called */
+ if(!GOOD_MULTI_HANDLE(multi))
+ return CURLM_BAD_HANDLE;
+
+#ifdef ENABLE_WAKEUP
+ /* the wakeup_pair variable is only written during init and cleanup,
+ making it safe to access from another thread after the init part
+ and before cleanup */
+ if(multi->wakeup_pair[1] != CURL_SOCKET_BAD) {
+ char buf[1];
+ buf[0] = 1;
+ while(1) {
+ /* swrite() is not thread-safe in general, because concurrent calls
+ can have their messages interleaved, but in this case the content
+ of the messages does not matter, which makes it ok to call.
+
+ The write socket is set to non-blocking, this way this function
+ cannot block, making it safe to call even from the same thread
+ that will call Curl_multi_wait(). If swrite() returns that it
+ would block, it's considered successful because it means that
+ previous calls to this function will wake up the poll(). */
+ if(swrite(multi->wakeup_pair[1], buf, sizeof(buf)) < 0) {
+ int err = SOCKERRNO;
+ int return_success;
+#ifdef USE_WINSOCK
+ return_success = WSAEWOULDBLOCK == err;
+#else
+ if(EINTR == err)
+ continue;
+ return_success = EWOULDBLOCK == err || EAGAIN == err;
+#endif
+ if(!return_success)
+ return CURLM_WAKEUP_FAILURE;
+ }
+ return CURLM_OK;
+ }
+ }
+#endif
+ return CURLM_WAKEUP_FAILURE;
}
/*
@@ -2309,6 +2412,11 @@ CURLMcode curl_multi_cleanup(struct Curl_multi *multi)
Curl_hash_destroy(&multi->hostcache);
Curl_psl_destroy(&multi->psl);
+
+#ifdef ENABLE_WAKEUP
+ sclose(multi->wakeup_pair[0]);
+ sclose(multi->wakeup_pair[1]);
+#endif
free(multi);
return CURLM_OK;
diff --git a/lib/multihandle.h b/lib/multihandle.h
index b65bd9638..a26fb619a 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -24,6 +24,7 @@
#include "conncache.h"
#include "psl.h"
+#include "socketpair.h"
struct Curl_message {
struct curl_llist_element list;
@@ -66,6 +67,10 @@ typedef enum {
#define CURLPIPE_ANY (CURLPIPE_MULTIPLEX)
+#if defined(USE_SOCKETPAIR) && !defined(USE_BLOCKING_SOCKETS)
+#define ENABLE_WAKEUP
+#endif
+
/* This is the struct known as CURLM on the outside */
struct Curl_multi {
/* First a simple identifier to easier detect if a user mix up
@@ -134,6 +139,11 @@ struct Curl_multi {
previous callback */
bool in_callback; /* true while executing a callback */
long max_concurrent_streams; /* max concurrent streams client to support */
+
+#ifdef ENABLE_WAKEUP
+ curl_socket_t wakeup_pair[2]; /* socketpair() used for wakeup
+ 0 is used for read, 1 is used for write */
+#endif
};
#endif /* HEADER_CURL_MULTIHANDLE_H */
diff --git a/lib/strerror.c b/lib/strerror.c
index ba2e7a6f9..baf5451ae 100644
--- a/lib/strerror.c
+++ b/lib/strerror.c
@@ -389,6 +389,9 @@ curl_multi_strerror(CURLMcode error)
case CURLM_RECURSIVE_API_CALL:
return "API function called from within callback";
+ case CURLM_WAKEUP_FAILURE:
+ return "Wakeup is unavailable or failed";
+
case CURLM_LAST:
break;
}