libcurl-thread.3: Consolidate thread safety info

This is a new document to consolidate our thread safety information from
several documents (curl-www:features, libcurl.3, libcurl-tutorial.3).
Each document's section on multi-threading will now point to this one.

1 files changed, 2 insertions, 52 deletions

diff --git a/docs/libcurl/libcurl-tutorial.3 b/docs/libcurl/libcurl-tutorial.3
index 11b019011..2563a881f 100644
--- a/docs/libcurl/libcurl-tutorial.3
+++ b/docs/libcurl/libcurl-tutorial.3
@@ -256,58 +256,8 @@ complication for you. Given simply the URL to a file, libcurl will take care
 of all the details needed to get the file moved from one machine to another.
 
 .SH "Multi-threading Issues"
-The first basic rule is that you must \fBnever\fP simultaneously share a
-libcurl handle (be it easy or multi or whatever) between multiple
-threads. Only use one handle in one thread at any time. You can pass the
-handles around among threads, but you must never use a single handle from more
-than one thread at any given time.
-
-libcurl is completely thread safe, except for two issues: signals and SSL/TLS
-handlers. Signals are used for timing out name resolves (during DNS lookup) -
-when built without using either the c-ares or threaded resolver backends.
-
-If you are accessing HTTPS or FTPS URLs in a multi-threaded manner, you are
-then of course using the underlying SSL library multi-threaded and those libs
-might have their own requirements on this issue. Basically, you need to
-provide one or two functions to allow it to function properly. For all
-details, see this:
-
-OpenSSL
-
- http://www.openssl.org/docs/crypto/threads.html#DESCRIPTION
-
-GnuTLS
-
- http://gnutls.org/manual/html_node/Thread-safety.html
-
-NSS
-
- is claimed to be thread-safe already without anything required.
-
-PolarSSL
-
- Required actions unknown.
-
-yassl
-
- Required actions unknown.
-
-axTLS
-
- Required actions unknown.
-
-Secure Transport
-
- The engine is fully thread-safe, and no additional steps are required.
-
-When using multiple threads you should set the \fICURLOPT_NOSIGNAL(3)\fP
-option to 1 for all handles. Everything will or might work fine except that
-timeouts are not honored during the DNS lookup - which you can work around by
-building libcurl with c-ares support. c-ares is a library that provides
-asynchronous name resolves. On some platforms, libcurl simply will not
-function properly multi-threaded unless this option is set.
-
-Also, note that \fICURLOPT_DNS_USE_GLOBAL_CACHE(3)\fP is not thread-safe.
+libcurl is thread safe but there are a few exceptions. Refer to
+\fIlibcurl-thread(3)\fP for more information.
 
 .SH "When It Doesn't Work"
 There will always be times when the transfer fails for some reason. You might