diff options
Diffstat (limited to 'erts/doc/src/erl_driver.xml')
| -rw-r--r-- | erts/doc/src/erl_driver.xml | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/erts/doc/src/erl_driver.xml b/erts/doc/src/erl_driver.xml index 2fb03954b6..8e18dd6657 100644 --- a/erts/doc/src/erl_driver.xml +++ b/erts/doc/src/erl_driver.xml @@ -1638,12 +1638,19 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len <fsummary>Cancel an asynchronous call</fsummary> <desc> <marker id="driver_async_cancel"></marker> - <p>This function cancels an asynchronous operation, by removing - it from the queue. Only functions in the queue can be - cancelled; if a function is executing, it's too late to - cancel it. The <c>async_free</c> function is also called.</p> - <p>The return value is 1 if the operation was removed from the - queue, otherwise 0.</p> + <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-R16. It will currently always fail, + and return 0.</p> + <warning><p><c>driver_async_cancel()</c> is deferred and will + be removed in the OTP-R16 release.</p> + </warning> + </desc> </func> <func> |