NAME queue_handler -- an 'infinite' pipe (FIFO) handler. (V37) SYNOPSIS Open("PIPE:[channel_name][[/[buf_size]][/max_buffers]]]"); FUNCTION Queue-handler takes data from the output channel, buffers it up, allocating more memory as needed, and sends it to the input channel, as requested by the applications. Queue-handler never locks the output channel unless max_buffers was specified. Buffer size can be specified only on the first reference to a particular channel. Queue-handler works by invoking a seperate process every time an open packet is received, and uses a FIFO buffer pool approach to track the actual data. INPUTS channel_name - unique channel name to specify. Must begin with a non-numeric character. The channel_name is optional. buf_size - Size in bytes of the buffers to allocate (default is 4096). The buf_size is optional. max_buffers - maximum number of buffers allowed. Will suspend the output channel if exceeded. A max_buffers value of 0 indicates there should be no fixed limit on the number of buffers allocated. PACKETS ACTION_FINDINPUT ACTION_FINDOUTPUT ACTION_FINDUPDATE ACTION_READ ACTION_WRITE ACTION_END ACTION_IS_FILESYSTEM MOUNTLIST ENTRIES This is the default mountlist entry used for Queue-Handler: PIPE: Handler = L:Queue-Handler Priority = 5 StackSize = 3000 GlobVec = -1 # Below is an extended mountlist entry which lets you specify a default number of buffers, and their size. There are some extra fields added at the end of the mountlist entry which aren't used for anything, but the Mount command requires that these fields be present. In this mountlist, the "Buffers" field indicates the default maximum number of buffers, and "SectorSize" indicates the size of these buffers. PIPE: FileSystem = L:Queue-Handler Priority = 5 StackSize = 3000 GlobVec = -1 SectorSize = 1024 Buffers = 2 /* these are unused, but required by Mount */ Surfaces = 1 SectorsPerTrack = 1 LowCyl = 0 HighCyl = 1 Device = "" Unit = 0 # EXAMPLE From process 1: list >pipe: work: all From process 2: type pipe: To gather the results of several C compilations: lc >pipe:ll foo lc >pipe:ll bar lc >pipe:ll road lc >pipe:ll kill type pipe:ll To use channel names: list >pipe:crazy copy #?.c to >pipe:all_c/32000 ;Specifies a channel 'all_c' and ;a buffer size of 32000 ;bytes To set a limit on the number of buffers to 5: dir >pipe://5 ; create a channel without a channel-name, and ; only allow 5 buffer entries. BUGS Full checking is not done to ensure that the application can't read from a write channel or vice-versa. The results of this operation shall be undefined. Don't do it.
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