snuyanzin commented on code in PR #26250:
URL: https://github.com/apache/flink/pull/26250#discussion_r1980897961
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flink-table/flink-table-common/src/main/java/org/apache/flink/table/functions/ProcessTableFunction.java:
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@@ -351,9 +439,158 @@ public interface Context {
/**
* Clears all state entries within the virtual partition once the
eval() method returns.
*
- * <p>Semantically this is equal to calling {@link
#clearState(String)} on all state
+ * <p>Semantically, this is equal to calling {@link
#clearState(String)} on all state
* entries.
*/
void clearAllState();
+
+ /** Clears all timers within the virtual partition. */
+ void clearAllTimers();
+
+ /** Clears the virtual partition including timers and state. */
+ void clearAll();
+ }
+
+ /**
+ * A context that gives access to Flink's concepts of time and timers.
+ *
+ * <p>An event can have an event-time timestamp assigned. The timestamp
can be accessed using
+ * the {@link #time()} method.
+ *
+ * <p>Timers allow for continuing the processing at a later point in time.
This makes waiting,
+ * synchronization, or timeouts possible. A timer fires for the registered
time when the
+ * watermark progresses the logical clock.
+ *
+ * <p>Flink takes care of storing and restoring timers during failures or
restarts. Thus, timers
+ * are a special kind of state. Similarly, timers are scoped to a virtual
processor defined by
+ * the PARTITION BY clause. A timer can only be registered and deleted in
the current virtual
+ * processor.
+ *
+ * @param <TimeType> conversion class of timestamps, see {@link
Context#timeContext(Class)}
+ */
+ @PublicEvolving
+ public interface TimeContext<TimeType> {
+
+ /**
+ * Returns the timestamp of the currently processed event.
+ *
+ * <p>An event can be either the row of a table or a firing timer:
+ *
+ * <h1>Row event timestamp</h1>
+ *
+ * <p>The timestamp of the row currently being processed within the
{@code eval()} method.
+ *
+ * <p>Powered by the function call's {@code on_time} argument, this
method will return the
+ * content of the referenced time attribute column. Returns {@code
null} if the {@code
+ * on_time} argument doesn't reference a time attribute column in the
currently processed
+ * table.
+ *
+ * <h1>Timer event timestamp</h1>
+ *
+ * <p>The timestamp of the firing timer currently being processed
within the {@code
+ * onTimer()} method.
+ *
+ * @return the event-time timestamp, or {@code null} if no timestamp
is present
+ */
+ TimeType time();
+
+ /**
+ * Returns the current event-time watermark.
+ *
+ * <p>Watermarks are generated in sources and sent through the
topology for advancing the
+ * logical clock in each Flink subtask. The current watermark of a
Flink subtask is the
+ * global minimum watermark of all inputs (i.e. across all parallel
inputs and table
+ * partitions).
+ *
+ * <p>This method returns the current watermark of the Flink subtask
that evaluates the PTF.
+ * Thus, the returned timestamp represents the entire Flink subtask,
independent of the
+ * currently processed partition. This behavior is similar to a call
to {@code SELECT
+ * CURRENT_WATERMARK(...)} in SQL.
+ *
+ * <p>If a watermark was not received from all inputs, the method
returns {@code null}.
+ *
+ * <p>In case this method is called within the {@code onTimer()}
method, the returned
+ * watermark is the triggering watermark that currently fires the
timer.
+ *
+ * @return the current watermark of the Flink subtask, or {@code null}
if no common logical
+ * time could be determined from the inputs
+ */
+ TimeType currentWatermark();
+
+ /**
+ * Registers a timer under the given name.
+ *
+ * <p>The timer fires when the {@link #currentWatermark()} advances
the logical clock of the
+ * Flink subtask to a timestamp later or equal to the desired
timestamp. In other words: A
+ * timer only fires if a watermark was received from all inputs and
the timestamp is smaller
+ * or equal to the minimum of all received watermarks.
+ *
+ * <p>Timers can be named for distinguishing them in the {@code
onTimer()} method.
+ * Registering a timer under the same name twice will replace an
existing timer.
Review Comment:
Should it then return for instance `boolean`or timer object indicating
whether existing timer was replaced or not? Similar to for example `put` method
in `java.util.Map`?
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