Inline Tasks

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As stated previously, workflow's code is processed multiple times, so it should not contain non-deterministic instructions either any instruction with side effects. When this is the case, we must put those within a task. For simple instructions (as getting a random number or the current date), it can be tedious to do so.

The inline function provides an easy way to "inline" such a task. The provided lambda is processed by the workflow executor only the first time. After that, the returned value will be found directly from the workflow history.

Inline tasks should be used only for instructions that can not fail.

For example, we can use the current date in a workflow like this:

...
Date now = inline(() -> new Date());
...
...
val now = inline { Date() }
...

Typical use cases of inline tasks are:

  • using environment variables
  • using current date
  • using random values
  • logging
// get (non-determistic) env variable
String home = inline(() -> System.getEnv("JAVA_HOME"));

// get (non-determistic) current date
Date now = inline(() -> new Date());

// get (non-determistic) random value
Integer random = inline(() -> new Random().nextInt(1000));

// display (side-effect)
inlineVoid(() -> System.out.println("log"));

// logging (side-effect)
inlineVoid(() -> logger.info("starting"));
// get (non-determistic) env variable
val home = inline { System.getEnv("JAVA_HOME") }

// get (non-determistic) current date
val now = inline { Date() }

// get (non-determistic) random value
val random = inline { Random().nextInt(1000) }

// display (side-effect)
inline { println("log") }

// logging (side-effect)
inline { logger.info("starting") }
Edit this page on GitHub Updated at Sun, Jul 3, 2022