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a whole new section on persitant connections and how they're treated

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internally
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Daniel Stenberg 2001-03-13 08:16:54 +00:00
parent 20ddd35669
commit 7d562bb685
1 changed files with 38 additions and 8 deletions
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docs/INTERNALS
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@ -1,4 +1,4 @@
Updated for curl 7.6 on January 26, 2001 Updated for curl 7.7 on March 13, 2001
_ _ ____ _ _ _ ____ _
___| | | | _ \| | ___| | | | _ \| |
/ __| | | | |_) | | / __| | | | |_) | |
@ -103,8 +103,9 @@ Library
lib/sendf.c) function to send printf-style formatted data to the remote host lib/sendf.c) function to send printf-style formatted data to the remote host
and when they're ready to make the actual file transfer they call the and when they're ready to make the actual file transfer they call the
Curl_Transfer() function (in lib/transfer.c) to setup the transfer and Curl_Transfer() function (in lib/transfer.c) to setup the transfer and
returns. curl_transfer() then calls _Tranfer() in lib/transfer.c that returns. Curl_perform() then calls Transfer() in lib/transfer.c that performs
performs the entire file transfer. the entire file transfer. Curl_perform() is what does the main "connect - do
- transfer - done" loop. It loops if there's a Location: to follow.
During transfer, the progress functions in lib/progress.c are called at a During transfer, the progress functions in lib/progress.c are called at a
frequent interval (or at the user's choice, a specified callback might get frequent interval (or at the user's choice, a specified callback might get
@ -160,7 +161,7 @@ Library
URL encoding and decoding, called escaping and unescaping in the source code, URL encoding and decoding, called escaping and unescaping in the source code,
is found in lib/escape.c. is found in lib/escape.c.
While transfering data in _Transfer() a few functions might get While transfering data in Transfer() a few functions might get
used. curl_getdate() in lib/getdate.c is for HTTP date comparisons (and used. curl_getdate() in lib/getdate.c is for HTTP date comparisons (and
more). more).
@ -182,6 +183,34 @@ Library
exists in lib/getpass.c. libcurl offers a custom callback that can be used exists in lib/getpass.c. libcurl offers a custom callback that can be used
instead of this, but it doesn't change much to us. instead of this, but it doesn't change much to us.
Persistant Connections
======================
With curl 7.7, we added persistant connection support to libcurl which has
introduced a somewhat different treatmeant of things inside of libcurl.
o The 'UrlData' struct returned in the curl_easy_init() call must never
hold connection-oriented data. It is meant to hold the root data as well
as all the options etc that the library-user may choose.
o The 'UrlData' struct holds the cache array of pointers to 'connectdata'
structs. There's one connectdata struct for each connection that libcurl
knows about.
o This also enables the 'curl handle' to be reused on subsequent transfers,
something that was illegal in pre-7.7 versions.
o When we are about to perform a transfer with curl_easy_perform(), we first
check for an already existing connection in the cache that we can use,
otherwise we create a new one and add to the cache. If the cache is full
already when we add a new connection, we close one of the present ones. We
select which one to close dependent on the close policy that may have been
previously set.
o When the tranfer operation is complete, we try to leave the connection open.
Particular options may tell us not to, and protocols may signal closure on
connections and then we don't keep it open of course.
o When curl_easy_cleanup() is called, we close all still opened connections.
You do realize that the curl handle must be re-used in order for the
persistant connections to work.
Library Symbols Library Symbols
=============== ===============
@ -256,8 +285,8 @@ Test Suite
httpserver.pl and ftpserver.pl before all the test cases are performed. The httpserver.pl and ftpserver.pl before all the test cases are performed. The
test suite currently only runs on unix-like platforms. test suite currently only runs on unix-like platforms.
You'll find a complete description of the test case data files in the README You'll find a complete description of the test case data files in the
file in the test directory. tests/README file.
The test suite automatically detects if curl was built with the memory The test suite automatically detects if curl was built with the memory
debugging enabled, and if it was it will detect memory leaks too. debugging enabled, and if it was it will detect memory leaks too.
@ -269,6 +298,7 @@ Building Releases
released, run the 'maketgz' script (using 'make distcheck' will give you a released, run the 'maketgz' script (using 'make distcheck' will give you a
pretty good view on the status of the current sources). maketgz prompts for pretty good view on the status of the current sources). maketgz prompts for
version number of the client and the library before it creates a release version number of the client and the library before it creates a release
archive. archive. maketgz uses 'make dist' for the actual archive building, why you
need to fill in the Makefile.am files properly for which files that should
be included in the release archives.
You must have autoconf installed to build release archives.