class ReadIfExistsWatcher extends SingletonQueryWatcher implements IfExistsWatcher
QueryWatcher
for non-transactional if
exists reads. Resolves with the first matching
transition where the transaction is null
and the entry
is visible (the entry's current state is ignored) or if
the locked entry set goes empty.Modifier and Type | Field and Description |
---|---|
private boolean |
backlogFinished
Set
true once the query thread is
done processing the backlog. |
private Set |
lockedEntries
The set of entries that would match but are currently
unavailable (e.g. they are locked).
|
startOrdinal
Constructor and Description |
---|
ReadIfExistsWatcher(long expiration,
long timestamp,
long startOrdinal,
Set lockedEntries)
Create a new
ReadIfExistsWatcher . |
Modifier and Type | Method and Description |
---|---|
(package private) boolean |
catchUp(EntryTransition transition,
long now)
Process a transition which was posted before the watcher was
placed in
TransitionWatchers object. |
void |
caughtUp()
Once the backlog is complete we can resolve if
lockedEntries is/becomes empty.
|
(package private) boolean |
isInterested(EntryTransition transition,
long ordinal)
Return
true if this watcher cares about a given
visibility transition. |
boolean |
isLockedEntrySetEmpty()
If the query has been resolved by the locked entry set
becoming empty returns
true , otherwise
return false . |
(package private) void |
process(EntryTransition transition,
long now)
Process the given transition.
|
addTemplateHandle, getServer, isResolved, resolve, resolvedWithEntry, resolvedWithThrowable, waitOnResolution
getExpiration, removeIfExpired
compareTo
private final Set lockedEntries
private boolean backlogFinished
true
once the query thread is
done processing the backlog. Once this is
true
it is ok to resolve if
lockedEntries
is empty.ReadIfExistsWatcher(long expiration, long timestamp, long startOrdinal, Set lockedEntries)
ReadIfExistsWatcher
.expiration
- the initial expiration time
for this TransitionWatcher
in
milliseconds since the beginning of the epoch.timestamp
- the value that is used
to sort TransitionWatcher
s.startOrdinal
- the highest ordinal associated
with operations that are considered to have occurred
before the operation associated with this watcher.lockedEntries
- Set of entries (by their IDs)
that match but are unavailable. Must be non-empty.
Keeps a reference to this object.NullPointerException
- if lockedEntries
is
null
.boolean isInterested(EntryTransition transition, long ordinal)
TransitionWatcher
true
if this watcher cares about a given
visibility transition. Assumes the transitioning entry matches
the template in the TemplateHandle
associated with
this watcher. This method should return a value even if the
expiration time has been reached or remove
has
been called. This call should not obtain any locks.isInterested
in class TransitionWatcher
transition
- A EntryTransition
that
describes the transition and what
entry is transitioning. This method
will assume that transition.getHandle
returns a non-null value.ordinal
- The ordinal associated with transition
.true
if this watcher is interested
in the indicated transition and false
otherwise.void process(EntryTransition transition, long now)
TransitionWatcher
TemplateHandle
associated with this
watcher and that isInterested
returned
true
. This call may make changes to the passed
EntryHandle
that will prevent it from being used by
other watchers. If remove
has been called or the
expiration time of this watcher has passed, this call should have no
effect. This call may cause the watcher to be removed.process
in class TransitionWatcher
transition
- A EntryTransition
that
describes the transition and what
entry is transitioning. This method
will assume that transition.getHandle
returns a non-null value.now
- An estimate of the current time (not the time
when the event occured).boolean catchUp(EntryTransition transition, long now)
QueryWatcher
TransitionWatchers
object. Assumes that
the entry in the transition matches matches the template in the
TemplateHandle
associated with this watcher. Does
not assume isInterested
has been called.catchUp
in class QueryWatcher
transition
- A EntryTransition
that
describes the transition and what
entry is transitioning. This method
will assume that transition.getHandle
returns a non-null value.now
- An estimate of the current time (not the time
when the event occured).true
if the query has been resolved, and
false
otherwise. Note, even if this
call returns true
, waitOnResolution
must still be called.public void caughtUp()
caughtUp
in interface IfExistsWatcher
public boolean isLockedEntrySetEmpty()
IfExistsWatcher
true
, otherwise
return false
.isLockedEntrySetEmpty
in interface IfExistsWatcher
true
if locked entry set
associated with this query is empty.Copyright 2007-2013, multiple authors.
Licensed under the Apache License, Version 2.0, see the NOTICE file for attributions.