1 files changed, 142 insertions, 0 deletions
diff --git a/include/dnsjit/core/channel.lua b/include/dnsjit/core/channel.lua
new file mode 100644
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+++ b/include/dnsjit/core/channel.lua
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+-- Copyright (c) 2018-2021, OARC, Inc.
+-- All rights reserved.
+--
+-- This file is part of dnsjit.
+--
+-- dnsjit is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- dnsjit is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with dnsjit.  If not, see <http://www.gnu.org/licenses/>.
+
+-- dnsjit.core.channel
+-- Send data to another thread
+--   local chan = require("dnsjit.core.channel").new()
+--   local thr = require("dnsjit.core.thread").new()
+--   thr:start(function(thr)
+--       local chan = thr:pop()
+--       local obj = chan:get()
+--       ...
+--   end)
+--   thr:push(chan)
+--   chan:put(...)
+--   chan:close()
+--   thr:stop()
+--
+-- A channel can be used to send data to another thread, this is done by
+-- putting a pointer to the data into a wait-free and lock-free ring buffer
+-- (concurrency kit).
+-- The channel uses the single producer, single consumer model (SPSC) so
+-- there can only be one writer and one reader.
+-- .SS Attributes
+-- .TP
+-- int closed
+-- Is 1 if the channel has been closed.
+module(...,package.seeall)
+
+require("dnsjit.core.channel_h")
+local ffi = require("ffi")
+local C = ffi.C
+
+local t_name = "core_channel_t"
+local core_channel_t
+local Channel = {}
+
+-- Create a new Channel, use the optional
+-- .I capacity
+-- to specify the capacity of the channel (buffer).
+-- Capacity must be a power-of-two greater than or equal to 4.
+-- Default capacity is 2048.
+function Channel.new(capacity)
+    if capacity == nil then
+        capacity = 2048
+    end
+    local self = core_channel_t()
+    C.core_channel_init(self, capacity)
+    ffi.gc(self, C.core_channel_destroy)
+    return self
+end
+
+-- Return the Log object to control logging of this instance or module.
+function Channel:log()
+    if self == nil then
+        return C.core_channel_log()
+    end
+    return self._log
+end
+
+-- Return information to use when sharing this object between threads.
+function Channel:share()
+    return ffi.cast("void*", self), t_name.."*", "dnsjit.core.channel"
+end
+
+-- Put an object into the channel, if the channel is full then it will
+-- stall and wait until space becomes available.
+-- Object may be nil.
+function Channel:put(obj)
+    C.core_channel_put(self, obj)
+end
+
+-- Try and put an object into the channel.
+-- Returns 0 on success.
+function Channel:put(obj)
+    C.core_channel_try_put(self, obj)
+end
+
+-- Get an object from the channel, if the channel is empty it will wait until
+-- an object is available.
+-- Returns nil if the channel is closed or if a nil object was explicitly put
+-- into the channel.
+function Channel:get()
+    return C.core_channel_get(self)
+end
+
+-- Try and get an object from the channel.
+-- Returns nil if there was no objects to get.
+function Channel:try_get()
+    return C.core_channel_try_get(self)
+end
+
+-- Return number of enqueued objects.
+function Channel:size()
+    return C.core_channel_size(self)
+end
+
+-- Returns true when channel is full.
+function Channel:full()
+    return C.core_channel_full(self)
+end
+
+-- Close the channel.
+function Channel:close()
+    C.core_channel_close(self)
+end
+
+-- Return the C functions and context for receiving objects.
+function Channel:receive()
+    return C.core_channel_receiver(), self
+end
+
+-- Set the receiver to pass objects to.
+-- NOTE; The channel keeps no reference of the receiver, it needs to live as
+-- long as the channel does.
+function Channel:receiver(o)
+    self.recv, self.ctx = o:receive()
+end
+
+-- Retrieve all objects from the channel and send it to the receiver.
+function Channel:run()
+    C.core_channel_run(self)
+end
+
+core_channel_t = ffi.metatype(t_name, { __index = Channel })
+
+-- dnsjit.core.thread (3)
+return Channel