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libcurl-thread.3: minor reformatting

This commit is contained in:
Daniel Stenberg 2015-07-31 23:19:02 +02:00
parent 23b84e448f
commit c8331f515e
1 changed files with 46 additions and 65 deletions
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111
docs/libcurl/libcurl-thread.3
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@ -23,7 +23,7 @@
.TH libcurl-thread 3 "13 Jul 2015" "libcurl" "libcurl thread safety" .TH libcurl-thread 3 "13 Jul 2015" "libcurl" "libcurl thread safety"
.SH NAME .SH NAME
libcurl-thread \- libcurl thread safety libcurl-thread \- libcurl thread safety
.SH "Multi-threading Issues" .SH "Multi-threading with libcurl"
libcurl is thread safe but has no internal thread synchronization. You may have libcurl is thread safe but has no internal thread synchronization. You may have
to provide your own locking should you meet any of the thread safety exceptions to provide your own locking should you meet any of the thread safety exceptions
below. below.
@ -35,80 +35,61 @@ handle from more than one thread at any given time.
\fBShared objects.\fP You can share certain data between multiple handles by \fBShared objects.\fP You can share certain data between multiple handles by
using the share interface but you must provide your own locking and set using the share interface but you must provide your own locking and set
\fIcurl_share_setopt(3)\fP CURLSHOPT_LOCKFUNC and CURLSHOPT_UNLOCKFUNC. \fIcurl_share_setopt(3)\fP CURLSHOPT_LOCKFUNC and CURLSHOPT_UNLOCKFUNC.
.SH TLS
\fBSSL/TLS handlers.\fP If you are accessing HTTPS or FTPS URLs in a If you are accessing HTTPS or FTPS URLs in a multi-threaded manner, you are
multi-threaded manner, you are then of course using the underlying SSL library then of course using the underlying SSL library multi-threaded and those libs
multi-threaded and those libs might have their own requirements on this issue. might have their own requirements on this issue. You may need to provide one
You may need to provide one or two functions to allow it to function properly: or two functions to allow it to function properly:
.RS
.IP OpenSSL .IP OpenSSL
http://www.openssl.org/docs/crypto/threads.html#DESCRIPTION
http://www.openssl.org/docs/crypto/threads.html#DESCRIPTION http://curl.haxx.se/libcurl/c/opensslthreadlock.html
http://curl.haxx.se/libcurl/c/opensslthreadlock.html
.IP GnuTLS .IP GnuTLS
http://gnutls.org/manual/html_node/Thread-safety.html
http://gnutls.org/manual/html_node/Thread-safety.html
.IP NSS .IP NSS
thread-safe already without anything required.
is claimed to be thread-safe already without anything required.
.IP PolarSSL .IP PolarSSL
Required actions unknown.
Required actions unknown.
.IP yassl .IP yassl
Required actions unknown.
Required actions unknown.
.IP axTLS .IP axTLS
Required actions unknown.
Required actions unknown.
.IP Secure-Transport .IP Secure-Transport
The engine is used by libcurl in a way that is fully thread-safe.
The engine is used by libcurl in a way that is fully thread-safe.
.IP WinSSL .IP WinSSL
The engine is used by libcurl in a way that is fully thread-safe.
The engine is used by libcurl in a way that is fully thread-safe.
.IP wolfSSL .IP wolfSSL
The engine is used by libcurl in a way that is fully thread-safe.
The engine is used by libcurl in a way that is fully thread-safe. .SH "Other areas of caution"
.RE .IP Signals
Signals are used for timing out name resolves (during DNS lookup) - when built
\fBSignals.\fP Signals are used for timing out name resolves (during DNS without using either the c-ares or threaded resolver backends. When using
lookup) - when built without using either the c-ares or threaded resolver multiple threads you should set the \fICURLOPT_NOSIGNAL(3)\fP option to 1L for
backends. When using multiple threads you should set the all handles. Everything will or might work fine except that timeouts are not
\fICURLOPT_NOSIGNAL(3)\fP option to 1L for all handles. Everything will or honored during the DNS lookup - which you can work around by building libcurl
might work fine except that timeouts are not honored during the DNS lookup - with c-ares support. c-ares is a library that provides asynchronous name
which you can work around by building libcurl with c-ares support. c-ares is a resolves. On some platforms, libcurl simply will not function properly
library that provides asynchronous name resolves. On some platforms, libcurl multi-threaded unless this option is set.
simply will not function properly multi-threaded unless this option is set. .IP "Name resolving"
\fBgethostby* functions and other system calls.\fP These functions, provided
\fBgethostby* functions and other system calls.\fP These functions, provided by by your operating system, must be thread safe. It is very important that
your operating system, must be thread safe. It is very important that libcurl libcurl can find and use thread safe versions of these and other system calls,
can find and use thread safe versions of these and other system calls, as as otherwise it can't function fully thread safe. Some operating systems are
otherwise it can't function fully thread safe. Some operating systems are known known to have faulty thread implementations. We have previously received
to have faulty thread implementations. We have previously received problem problem reports on *BSD (at least in the past, they may be working fine these
reports on *BSD (at least in the past, they may be working fine these days). days). Some operating systems that are known to have solid and working thread
Some operating systems that are known to have solid and working thread support support are Linux, Solaris and Windows.
are Linux, Solaris and Windows. .IP "curl_global_* functions"
These functions are not thread safe. If you are using libcurl with multiple
\fBcurl_global_* functions.\fP These functions are not thread safe. If you are threads it is especially important that before use you call
using libcurl with multiple threads it is especially important that before use \fIcurl_global_init(3)\fP or \fIcurl_global_init_mem(3)\fP to explicitly
you call \fIcurl_global_init(3)\fP or \fIcurl_global_init_mem(3)\fP to initialize the library and its dependents, rather than rely on the "lazy"
explicitly initialize the library and its dependents, rather than rely on the fail-safe initialization that takes place the first time
"lazy" fail-safe initialization that takes place the first time
\fIcurl_easy_init(3)\fP is called. For an in-depth explanation refer to \fIcurl_easy_init(3)\fP is called. For an in-depth explanation refer to
\fIlibcurl(3)\fP section \fBGLOBAL CONSTANTS\fP. \fIlibcurl(3)\fP section \fBGLOBAL CONSTANTS\fP.
.IP "Memory functions"
\fBMemory functions.\fP These functions, provided either by your operating These functions, provided either by your operating system or your own
system or your own replacements, must be thread safe. You can use replacements, must be thread safe. You can use \fIcurl_global_init_mem(3)\fP
\fIcurl_global_init_mem(3)\fP to set your own replacement memory functions. to set your own replacement memory functions.
.IP Non-safe functions
\fICURLOPT_DNS_USE_GLOBAL_CACHE(3)\fP is not thread-safe. \fICURLOPT_DNS_USE_GLOBAL_CACHE(3)\fP is not thread-safe.