Class One2OneChannelIntImpl
- All Implemented Interfaces:
ChannelInternalsInt
,One2OneChannelInt
Description
One2OneChannelIntImpl implements a one-to-one integer channel. Multiple readers or multiple writers are not allowed -- these are catered for byAny2OneChannelIntImpl
,
One2AnyChannelIntImpl
or
Any2AnyChannelIntImpl
.
The reading process may ALT
on this channel.
The writing process is committed (i.e. it may not back off).
The default semantics of the channel is that of CSP -- i.e. it is zero-buffered and fully synchronised. The reading process must wait for a matching writer and vice-versa.
However, the static methods of Channel
allow the creation of
a channel with a plug-in driver conforming to the
ChannelDataStoreInt
interface. This allows a variety of different channel semantics to be
introduced -- including buffered channels of user-defined capacity
(including infinite), overwriting channels (with various overwriting
policies) etc..
Standard examples are given in the org.jcsp.util.ints package, but
careful users may write their own.
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate Alternative
The Alternative class that controls the selectionprivate boolean
The synchronisation flagprivate int
The (invisible-to-users) buffer used to store the data for the channelprivate Object
The monitor synchronising reader and writer on this channelprivate boolean
Flag to deal with a spurious wakeup during a write -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic One2OneChannelInt[]
create
(int n) Creates an array of One2OneChannelInts.static One2OneChannelInt[]
create
(int n, ChannelDataStoreInt store) Creates an array of One2OneChannelInts using the specified ChannelDataStoreInt.static One2OneChannelInt
create
(ChannelDataStoreInt store) Creates a One2OneChannelIntImpl using the specified ChannelDataStoreInt.void
endRead()
in()
Returns theAltingChannelInputInt
object to use for this channel.out()
Returns theChannelOutputInt
object to use for this channel.int
read()
Reads an int from the channel.boolean
turns off Alternative selection for the channel.boolean
readerEnable
(Alternative alt) turns on Alternative selection for the channel.boolean
Returns whether there is data pending on this channel.void
readerPoison
(int strength) int
void
write
(int value) Writes an int to the channel.void
writerPoison
(int strength)
-
Field Details
-
rwMonitor
The monitor synchronising reader and writer on this channel -
hold
private int holdThe (invisible-to-users) buffer used to store the data for the channel -
empty
private boolean emptyThe synchronisation flag -
alt
The Alternative class that controls the selection -
spuriousWakeUp
private boolean spuriousWakeUpFlag to deal with a spurious wakeup during a write
-
-
Constructor Details
-
One2OneChannelIntImpl
One2OneChannelIntImpl()
-
-
Method Details
-
in
Returns theAltingChannelInputInt
object to use for this channel. AsOne2OneChannelIntImpl
implementsAltingChannelInputInt
itself, this method simply returns a reference to the object that it is called on.- Specified by:
in
in interfaceOne2OneChannelInt
- Returns:
- the
AltingChannelInputInt
object to use for this channel.
-
out
Returns theChannelOutputInt
object to use for this channel. AsOne2OneChannelIntImpl
implementsChannelOutputInt
itself, this method simply returns a reference to the object that it is called on.- Specified by:
out
in interfaceOne2OneChannelInt
- Returns:
- the
ChannelOutputInt
object to use for this channel.
-
read
public int read()Reads an int from the channel.- Specified by:
read
in interfaceChannelInternalsInt
- Returns:
- the integer read from the channel.
-
startRead
public int startRead()- Specified by:
startRead
in interfaceChannelInternalsInt
-
endRead
public void endRead()- Specified by:
endRead
in interfaceChannelInternalsInt
-
write
public void write(int value) Writes an int to the channel.- Specified by:
write
in interfaceChannelInternalsInt
- Parameters:
value
- the integer to write to the channel.
-
readerEnable
turns on Alternative selection for the channel. Returns true if the channel has data that can be read immediately.Note: this method should only be called by the Alternative class
- Specified by:
readerEnable
in interfaceChannelInternalsInt
- Parameters:
alt
- the Alternative class which will control the selection- Returns:
- true if the channel has data that can be read, else false
-
readerDisable
public boolean readerDisable()turns off Alternative selection for the channel. Returns true if the channel contained data that can be read.Note: this method should only be called by the Alternative class
- Specified by:
readerDisable
in interfaceChannelInternalsInt
- Returns:
- true if the channel has data that can be read, else false
-
readerPending
public boolean readerPending()Returns whether there is data pending on this channel.Note: if there is, it won't go away until you read it. But if there isn't, there may be some by the time you check the result of this method.
This method is provided for convenience. Its functionality can be provided by Pri Alting the channel against a SKIP guard, although at greater run-time and syntactic cost. For example, the following code fragment:
if (c.pending ()) { int x = c.read (); ... do something with x } else ( ... do something else }
is equivalent to:if (c_pending.priSelect () == 0) { int x = c.read (); ... do something with x } else ( ... do something else }
where earlier would have had to have been declared:final Alternative c_pending = new Alternative (new Guard[] {c, new Skip ()});
- Specified by:
readerPending
in interfaceChannelInternalsInt
- Returns:
- state of the channel.
-
create
Creates an array of One2OneChannelInts.- Parameters:
n
- the number of channels to create in the array- Returns:
- the array of One2OneChannelIntImpl
-
create
Creates a One2OneChannelIntImpl using the specified ChannelDataStoreInt.- Returns:
- the One2OneChannelIntImpl
-
create
Creates an array of One2OneChannelInts using the specified ChannelDataStoreInt.- Parameters:
n
- the number of channels to create in the array- Returns:
- the array of One2OneChannelIntImpl
-
readerPoison
public void readerPoison(int strength) - Specified by:
readerPoison
in interfaceChannelInternalsInt
-
writerPoison
public void writerPoison(int strength) - Specified by:
writerPoison
in interfaceChannelInternalsInt
-