key

Commentary

added in 0.1.0

Dynamically creates new instances of this generator.

If key is a supplied with an array, the generator runs for each unique element. If key is supplied as a function, the generator runs for each uniquely returned value. If that value is ever null, no more forks will be spawned.

Only one instance of a generator will run at a time for each fork key.

The fork key for each generator can be accessed through the var forkKey.

---

Examples

Forking on an array

If the fork key is an array, it will create a generator instance for each element in the specified order.

{
    "topic": "sensors",
    "fork": {
        "key": [
            "sensor #1",
            "sensor #2",
            "sensor #3"
        ]
    },
    "value": {
        "id": {
            "_gen": "var",
            "var": "forkKey"
        }
    },
    "localConfigs": {
        "maxEvents": 1
    }
}

[
    {
        "id": "sensor #1"
    },
    {
        "id": "sensor #2"
    },
    {
        "id": "sensor #3"
    }
]

Forking on a function

If the fork key is a function, it will create a generator instance for each returned value.

{
    "topic": "sensors",
    "fork": {
        "key": {
            "_gen": "sequentialString",
            "expr": "sensor-~d"
        }
    },
    "value": {
        "id": {
            "_gen": "var",
            "var": "forkKey"
        }
    },
    "localConfigs": {
        "maxEvents": 1
    }
}

[
    {
        "id": "sensor-0"
    },
    {
        "id": "sensor-1"
    },
    {
        "id": "sensor-2"
    },
    {
        "id": "sensor-3"
    }
]

Forking on a lookup

If the fork key is a lookup function, it will create generator instances in the order the looked up data was created.

Further, if any fork instances terminate, new forks will use the earliest (first-created) available keys. In other words, lookup keys are both used and recycled in order.

{
    "topic": "agents",
    "value": {
        "id": {
            "_gen": "sequentialString",
            "expr": "agent-~d"
        }
    },
    "localConfigs": {
        "maxEvents": 2
    }
}

[
    {
        "topic": "agents",
        "key": null,
        "value": {
            "id": "agent-0"
        },
        "headers": null
    },
    {
        "topic": "calls",
        "key": null,
        "value": {
            "callId": "call-0",
            "agentId": "agent-0"
        },
        "headers": null
    },
    {
        "topic": "agents",
        "key": null,
        "value": {
            "id": "agent-1"
        },
        "headers": null
    },
    {
        "topic": "calls",
        "key": null,
        "value": {
            "callId": "call-0",
            "agentId": "agent-1"
        },
        "headers": null
    },
    {
        "topic": "calls",
        "key": null,
        "value": {
            "callId": "call-0",
            "agentId": "agent-0"
        },
        "headers": null
    }
]

---

Specification

JSON schema

{
    "type": [
        "array",
        {
            "type": "object",
            "properties": {
                "_gen": {
                    "type": "string"
                }
            },
            "required": [
                "_gen"
            ]
        }
    ]
}