curl_easy_pause
curl_easy_pause
NAMESYNOPSIS
DESCRIPTION
RETURN VALUE
AVAILABILITY
MEMORY USE
SEE ALSO
NAME
curl_easy_pause - pause and unpause a connection
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_pause(CURL *handle, int bitmask );
DESCRIPTION
Using this function, you can explicitly mark a running connection to get paused, and you can unpause a connection that was previously paused.
A connection can be paused by using this function or by letting the read or the write callbacks return the proper magic return code (CURL_READFUNC_PAUSE and CURL_WRITEFUNC_PAUSE). A write callback that returns pause signals to the library that it couldn’t take care of any data at all, and that data will then be delivered again to the callback when the writing is later unpaused.
NOTE: while it may feel tempting, take care and notice that you cannot call this function from another thread.
When this function is called to unpause reading, the chance is high that you will get your write callback called before this function returns.
The handle argument is of course identifying the handle that operates on the connection you want to pause or unpause.
The
bitmask argument is a set of bits that sets the new
state of the connection. The following bits can be used:
CURLPAUSE_RECV
Pause receiving data. There will be no data received on this connection until this function is called again without this bit set. Thus, the write callback (CURLOPT_WRITEFUNCTION) won’t be called.
CURLPAUSE_SEND
Pause sending data. There will be no data sent on this connection until this function is called again without this bit set. Thus, the read callback (CURLOPT_READFUNCTION) won’t be called.
CURLPAUSE_ALL
Convenience define that pauses both directions.
CURLPAUSE_CONT
Convenience define that unpauses both directions
RETURN VALUE
CURLE_OK (zero) means that the option was set properly, and a non-zero return code means something wrong occurred after the new state was set. See the libcurl-errors(3) man page for the full list with descriptions.
AVAILABILITY
This function was added in libcurl 7.18.0. Before this version, there was no explicit support for pausing transfers.
MEMORY USE
When pausing a read by returning the magic return code from a write callback, the read data is already in libcurl’s internal buffers so it’ll have to keep it in an allocated buffer until the reading is again unpaused using this function.
If the downloaded data is compressed and is asked to get uncompressed automatically on download, libcurl will continue to uncompress the entire downloaded chunk and it will cache the data uncompressed. This has the side- effect that if you download something that is compressed a lot, it can result in a very large data amount needing to be allocated to save the data during the pause. This said, you should probably consider not using paused reading if you allow libcurl to uncompress data automatically.
SEE ALSO
curl_easy_cleanup(3), curl_easy_reset(3)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
