diff options
Diffstat (limited to 'erts/doc/src/erl_driver.xml')
| -rw-r--r-- | erts/doc/src/erl_driver.xml | 72 |
1 files changed, 39 insertions, 33 deletions
diff --git a/erts/doc/src/erl_driver.xml b/erts/doc/src/erl_driver.xml index c055d1ca9e..ad37813ac0 100644 --- a/erts/doc/src/erl_driver.xml +++ b/erts/doc/src/erl_driver.xml @@ -1,10 +1,10 @@ -<?xml version="1.0" encoding="latin1" ?> +<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE cref SYSTEM "cref.dtd"> <cref> <header> <copyright> - <year>2001</year><year>2013</year> + <year>2001</year><year>2014</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -315,10 +315,13 @@ <c>ERL_DRV_EXTENDED_MINOR_VERSION</c> will be incremented when new features are added. The runtime system uses the minor version of the driver to determine what features to use. - The runtime system will refuse to load a driver if the major + The runtime system will normally refuse to load a driver if the major versions differ, or if the major versions are equal and the minor version used by the driver is greater than the one used - by the runtime system.</p> + by the runtime system. Old drivers with lower major versions + will however be allowed after a bump of the major version during + a transition period of two major releases. Such old drivers might + however fail if deprecated features are used.</p> <p>The emulator will refuse to load a driver that does not use the extended driver interface, to allow for 64-bit capable drivers, @@ -745,7 +748,7 @@ typedef struct ErlIOVec { created and decrement it once when the port associated with the lock terminates. The emulator will also increment the reference count when an async job is enqueued and decrement - it after an async job has been invoked, or canceled. Besides + it after an async job has been invoked. Besides this, it is the responsibility of the driver to ensure that the reference count does not reach zero before the last use of the lock by the driver has been made. The reference count @@ -1035,7 +1038,9 @@ typedef struct ErlIOVec { <c>select</c>/<c>poll</c> can use). On windows, the Win32 API function <c>WaitForMultipleObjects</c> is used. This places other restrictions on the event object. - Refer to the Win32 SDK documentation.</p> + Refer to the Win32 SDK documentation. + On Enea OSE, the receive function is used. See the <seealso + marker="ose:ose_erl_driver"></seealso> for more details.</p> <p>The <c>on</c> parameter should be <c>1</c> for setting events and <c>0</c> for clearing them.</p> <p>The <c>mode</c> argument is a bitwise-or combination of @@ -1047,7 +1052,7 @@ typedef struct ErlIOVec { <seealso marker="driver_entry#ready_output">ready_output</seealso>. </p> <note> - <p>Some OS (Windows) do not differentiate between read and write events. + <p>Some OS (Windows and Enea OSE) do not differentiate between read and write events. The call-back for a fired event then only depends on the value of <c>mode</c>.</p> </note> <p><c>ERL_DRV_USE</c> specifies if we are using the event object or if we want to close it. @@ -1742,15 +1747,19 @@ typedef struct ErlIOVec { term consists of one to four elements in the array. The term first has a term type, and then arguments. The <c>port</c> parameter specifies the sending port.</p> - <p>Tuple and lists (with the exception of strings, see below), + <p>Tuples, maps and lists (with the exception of strings, see below), are built in reverse polish notation, so that to build a tuple, the elements are given first, and then the tuple - term, with a count. Likewise for lists.</p> + term, with a count. Likewise for lists and maps.</p> <p>A tuple must be specified with the number of elements. (The elements precede the <c>ERL_DRV_TUPLE</c> term.)</p> <p>A list must be specified with the number of elements, including the tail, which is the last term preceding <c>ERL_DRV_LIST</c>.</p> + <p>A map must be specified with the number of key-value pairs <c>N</c>. + The key-value pairs must precede the <c>ERL_DRV_MAP</c> in this order: + <c>key1,value1,key2,value2,...,keyN,valueN</c>. + Duplicate keys are not allowed.</p> <p>The special term <c>ERL_DRV_STRING_CONS</c> is used to "splice" in a string in a list, a string given this way is not a list per se, but the elements are elements of the @@ -1774,6 +1783,7 @@ ERL_DRV_PID ErlDrvTermData pid (from driver_connected(ErlDrvPort port) ERL_DRV_STRING_CONS char *str, int len ERL_DRV_FLOAT double *dbl ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len +ERL_DRV_MAP int sz </pre> <p>The unsigned integer data type <c>ErlDrvUInt</c> and the signed integer data type <c>ErlDrvSInt</c> are 64 bits wide @@ -1856,6 +1866,24 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len }; erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0])); ]]></code> + + <p>To build the map <c>#{key1 => 100, key2 => {200, 300}}</c>, the + following call could be made.</p> + <code type="none"><![CDATA[ + ErlDrvPort port = ... + ErlDrvTermData spec[] = { + ERL_DRV_ATOM, driver_mk_atom("key1"), + ERL_DRV_INT, 100, + ERL_DRV_ATOM, driver_mk_atom("key2"), + ERL_DRV_INT, 200, + ERL_DRV_INT, 300, + ERL_DRV_TUPLE, 2, + ERL_DRV_MAP, 2 + }; + erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0])); + ]]> + </code> + <p>If you want to pass a binary and don't already have the content of the binary in an <c>ErlDrvBinary</c>, you can benefit from using <c>ERL_DRV_BUF2BINARY</c> instead of creating an <c>ErlDrvBinary</c> @@ -1995,14 +2023,12 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len <c>async_invoke</c> and <c>async_free</c>. It's typically a pointer to a structure that contains a pipe or event that can be used to signal that the async operation completed. - The data should be freed in <c>async_free</c>, because it's - called if <c>driver_async_cancel</c> is called.</p> + The data should be freed in <c>async_free</c>.</p> <p>When the async operation is done, <seealso marker="driver_entry#ready_async">ready_async</seealso> driver entry function is called. If <c>ready_async</c> is null in the driver entry, the <c>async_free</c> function is called instead.</p> - <p>The return value is a handle to the asynchronous task, which - can be used as argument to <c>driver_async_cancel</c>.</p> + <p>The return value is a handle to the asynchronous task.</p> <note> <p>As of erts version 5.5.4.3 the default stack size for threads in the async-thread pool is 16 kilowords, @@ -2040,26 +2066,6 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len </desc> </func> <func> - <name><ret>int</ret><nametext>driver_async_cancel(long id)</nametext></name> - <fsummary>Cancel an asynchronous call</fsummary> - <desc> - <marker id="driver_async_cancel"></marker> - <p>This function used to cancel a scheduled asynchronous operation, - if it was still in the queue. It returned 1 if it succeeded, and - 0 if it failed.</p> - <p>Since it could not guarantee success, it was more or less useless. - The user had to implement synchronization of cancellation anyway. - It also unnecessarily complicated the implementation. Therefore, - as of OTP-R15B <c>driver_async_cancel()</c> is deprecated, and - scheduled for removal in OTP-R17. It will currently always fail, - and return 0.</p> - <warning><p><c>driver_async_cancel()</c> is deprecated and will - be removed in the OTP-R17 release.</p> - </warning> - - </desc> - </func> - <func> <name><ret>int</ret><nametext>driver_lock_driver(ErlDrvPort port)</nametext></name> <fsummary>Make sure the driver is never unloaded</fsummary> <desc> |