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A command line tool and library for transferring data with URL syntax, supporting DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS and WSS. libcurl offers a myriad of powerful features
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980659a2ca
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Daniel Stenberg 980659a2ca multi_socket: remind app if timeout didn't run 
BACKGROUND:

We have learned that on some systems timeout timers are inaccurate and
might occasionally fire off too early. To make the multi_socket API work
with this, we made libcurl execute timeout actions a bit early too if
they are within our MULTI_TIMEOUT_INACCURACY. (added in commit
2c72732ebf, present since 7.21.0)

Switching everything to the multi API made this inaccuracy problem
slightly more notable as now everyone can be affected.

Recently (commit 21091549c0) we tweaked that inaccuracy value to make
timeouts more accurate and made it platform specific. We also figured
out that we have code at places that check for fixed timeout values so
they MUST NOT run too early as then they will not trigger at all (see
commit be28223f35 and a691e04470) - so there are definitately problems
with running timeouts before they're supposed to run. (We've handled
that so far by adding the inaccuracy margin to those specific timeouts.)

The libcurl multi_socket API tells the application with a callback that
a timeout expires in N milliseconds (and it explicitly will not tell it
again for the same timeout), and the application is then supposed to
call libcurl when that timeout expires. When libcurl subsequently gets
called with curl_multi_socket_action(...CURL_SOCKET_TIMEOUT...), it
knows that the application thinks the timeout expired - and alas, if it
is within the inaccuracy level libcurl will run code handling that
handle.

If the application says CURL_SOCKET_TIMEOUT to libcurl and _isn't_
within the inaccuracy level, libcurl will not consider the timeout
expired and it will not tell the application again since the timeout
value is still the same.

NOW:

This change introduces a modified behavior here. If the application says
CURL_SOCKET_TIMEOUT and libcurl finds no timeout code to run, it will
inform the application about the timeout value - *again* even if it is
the same timeout that it already told about before (although libcurl
will of course tell it the updated time so that it'll still get the
correct remaining time). This way, we will not risk that the application
believes it has done its job and libcurl thinks the time hasn't come yet
to run any code and both just sit waiting. This also allows us to
decrease the MULTI_TIMEOUT_INACCURACY margin, but that will be handled
in a separate commit.

A repeated timeout update to the application risk that the timeout will
then fire again immediately and we have what basically is a busy-loop
until the time is fine even for libcurl. If that becomes a problem, we
need to address it.
2014-01-10 13:57:25 +01:00
CMake cmake: fix Windows build with IPv6 support 2013-11-09 00:07:32 +01:00
docs mk-ca-bundle.1: document -d 2014-01-07 23:51:01 +01:00
include Bumped copyright year to 2014 2014-01-02 23:53:49 +00:00
lib multi_socket: remind app if timeout didn't run 2014-01-10 13:57:25 +01:00
m4 configure: use icc options without space 2013-09-27 10:57:20 +02:00
packages packages: follow up fix for a47c142, 11e8066 and 92b9ae5 2014-01-05 20:13:55 +01:00
perl removed trailing whitespace 2011-12-30 03:36:18 +01:00
src login options: remove the ;[options] support from CURLOPT_USERPWD 2013-12-14 22:40:37 +01:00
tests runtests: disable memory tracking with threaded resolver 2014-01-08 13:20:29 +01:00
vs move msvc IDE related files to 'vs' directory tree 2013-02-13 17:14:21 +01:00
winbuild makefile: Added support for VC12 2014-01-08 02:26:42 +00:00
.gitattributes Tell git to not convert configure-related files. 2012-07-17 20:35:23 +02:00
.gitignore gitignore: ignore .dirstamp files 2013-12-18 14:35:56 +01:00
.travis.yml Adding a .travis.yml file to use the travis-ci.org 2013-10-21 23:15:16 +02:00
acinclude.m4 acinclude: fix --without-ca-path when cross-compiling 2013-09-04 00:01:03 +02:00
buildconf Revert changes relative to lib/*.[ch] recent renaming 2013-01-06 18:20:27 +01:00
buildconf.bat curl tool: renaming hugehelp files to tool_hugehelp 2012-12-26 23:30:54 +01:00
CHANGES CHANGES: move all contents from CHANGES to CHANGES.0 2010-06-21 22:27:39 +02:00
CHANGES.0 removed trailing whitespace 2011-12-30 03:36:18 +01:00
CMakeLists.txt CMakeLists.txt: add standard curl source code header 2014-01-01 22:35:59 +01:00
configure.ac Bumped copyright year to 2014 2014-01-02 23:53:49 +00:00
contributors.sh contributors: helper script to dig out contributors from git 2013-10-07 09:47:03 +02:00
COPYING Bumped copyright year to 2014 2014-01-02 23:53:49 +00:00
CTestConfig.cmake ENH: move dashboard location 2009-07-15 19:40:46 +00:00
curl-config.in curl-config.in: replace tabs by spaces 2013-06-22 22:08:42 +02:00
GIT-INFO curl tool: renaming hugehelp files to tool_hugehelp 2012-12-26 23:30:54 +01:00
install-sh install-sh: updated to support multiple source files as arguments 2013-02-13 15:47:54 +01:00
libcurl.pc.in build: prevent global LIBS from influencing src and lib build targets 2012-12-03 22:41:18 +01:00
log2changes.pl log2changes.pl: fix the Version output 2012-06-07 23:50:00 +02:00
MacOSX-Framework OS X framework: fix invalid symbolic link 2013-05-09 21:51:35 +02:00
Makefile.am move msvc IDE related files to 'vs' directory tree 2013-02-13 17:14:21 +01:00
Makefile.dist makefile: Added support for VC12 2014-01-08 02:26:42 +00:00
maketgz maketgz: make bzip2 creation work with Parallel BZIP2 too 2013-04-18 11:13:56 +02:00
missing renamed generated config.h to curl_config.h in order to avoid clashes when libcurl is used with other projects which also have a config.h. 2009-07-14 13:25:14 +00:00
mkinstalldirs install-sh: updated to support multiple source files as arguments 2013-02-13 15:47:54 +01:00
README various changes of CVS to git 2010-03-22 00:34:09 +01:00
RELEASE-NOTES RELEASE-NOTES: Synced with 8ae35102c4 2014-01-07 22:12:57 +00:00
TODO-RELEASE TODO-RELEASE: cleaned up, not really maintained lately 2013-04-08 08:32:10 +02:00

README 

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README

  Curl is a command line tool for transferring data specified with URL
  syntax. Find out how to use curl by reading the curl.1 man page or the
  MANUAL document. Find out how to install Curl by reading the INSTALL
  document.

  libcurl is the library curl is using to do its job. It is readily
  available to be used by your software. Read the libcurl.3 man page to
  learn how!

  You find answers to the most frequent questions we get in the FAQ document.

  Study the COPYING file for distribution terms and similar. If you distribute
  curl binaries or other binaries that involve libcurl, you might enjoy the
  LICENSE-MIXING document.

CONTACT

  If you have problems, questions, ideas or suggestions, please contact us
  by posting to a suitable mailing list. See http://curl.haxx.se/mail/

  All contributors to the project are listed in the THANKS document.

WEB SITE

  Visit the curl web site for the latest news and downloads:

        http://curl.haxx.se/

GIT

  To download the very latest source off the GIT server do this:

    git clone git://github.com/bagder/curl.git

  (you'll get a directory named curl created, filled with the source code)

NOTICE

  Curl contains pieces of source code that is Copyright (c) 1998, 1999
  Kungliga Tekniska Högskolan. This notice is included here to comply with the
  distribution terms.