| TclCurl(3) | TclCurl | TclCurl(3) |
TclCurl: - get a URL with FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, FILE, LDAP, LDAPS, IMAP, IMAPS, POP, POP3, SMTP, SMTPS and gopher syntax.
curl::multiinit
multiHandle addhandle
multiHandle removehandle
multiHandle configure
multiHandle perform
multiHandle active
multiHandle getinfo
multihandle cleanup
multihandle auto
curl::multistrerror errorCode
TclCurl's multi interface introduces several new abilities that the easy interface refuses to offer. They are mainly:
A few areas in the code are still using blocking code, even when used from the multi interface. While we certainly want and intend for these to get fixed in the future, you should be aware of the following current restrictions:
This procedure must be the first one to call, it returns a multiHandle that you need to use to invoke TclCurl procedures. The init MUST have a corresponding call to cleanup when the operation is completed.
RETURN VALUE
multiHandle to use.
Each single transfer is built up with an 'easy' handle, the kind we have been using so far with TclCurl, you must create them and setup the appropriate options for each of them. Then we add them to the 'multi stack' using the addhandle command.
If the easy handle is not set to use a shared or global DNS cache, it will be made to use the DNS cache that is shared between all easy handles within the multi handle.
When an easy handle has been added to a multi stack, you can not and you must not use perform on that handle!
multiHandle is the return code from the curl::multiinit call.
RETURN VALUE The possible return values are:
When a transfer is done or if we want to stop a transfer before it is completed, we can use the removehandle command. Once removed from the multi handle, we can again use other easy interface functions on it.
Please note that when a single transfer is completed, the easy handle is still left added to the multi stack. You need to remove it and then close or, possibly, set new options to it and add it again to the multi handle to start another transfer.
RETURN VALUE The possible return values are:
So far the only options are:
By setting this option, you can prevent the cache size to grow beyond the limit set by you. When the cache is full, curl closes the oldest one in the cache to prevent the number of open connections to increase.
This option is for the multi handle's use only, when using the easy interface you should instead use it's own maxconnects option.
Adding the easy handles to the multi stack does not start any transfer. Remember that one of the main ideas with this interface is to let your application drive. You drive the transfers by invoking perform. TclCurl will then transfer data if there is anything available to transfer. It'll use the callbacks and everything else we have setup in the individual easy handles. It'll transfer data on all current transfers in the multi stack that are ready to transfer anything. It may be all, it may be none.
When you call perform and the amount of running handles is changed from the previous call (or is less than the amount of easy handles you added to the multi handle), you know that there is one or more transfers less "running". You can then call getinfo to get information about each individual completed transfer. If an added handle fails very quickly, it may never be counted as a running handle.
RETURN VALUE If everything goes well, it returns the number of running handles, '0' if all are done. In case of error, it will return the error code.
This function only returns errors etc regarding the whole multi stack. Problems still might have occurred on individual transfers even when this function returns ok.
In order to know if any of the easy handles are ready to transfer data before invoking perform you can use the active command, it will return the number of transfers currently active.
RETURN VALUE The number of active transfers or '-1' in case of error.
This procedure returns very simple information about the transfers, you can get more detail information using the getinfo command on each of the easy handles.
RETURN VALUE A list with the following elements:
This procedure must be the last one to call for a multi stack, it is the opposite of the curl::multiinit procedure and must be called with the same multiHandle as input as the curl::multiinit call returned.
Using this command Tcl's event loop will take care of periodically invoking perform for you, before using it, you must have already added at least one easy handle to the multi handle.
The command option allows you to specify a command to invoke after all the easy handles have finished their transfers, even though I say it is an option, the truth is you must use this command to cleanup all the handles, otherwise the transfered files may not be complete.
This support is still in a very experimental state, it may still change without warning. Any and all comments are welcome.
You can find a couple of examples at tests/multi.
This procedure returns a string describing the error code passed in the argument.
tclcurl, curl.
| 3 October 2011 | TclCurl 7.22.0 |