sequence

Sequential execute the functions.

Function Arguments

Name	Type	Description
functions	list	The list of the function expression.

Description

The input of the next function is the output of the previous function. The concept is:

data = Func1(data)
data = Func2(data)
...

This function is very useful when you want to union the outputs of a series of probe functions.

Examples

Assume that we want to design a probe statement to probe general information from the device. The expected probed data should contain two fields:

• device_sku comes from the command cros_config /identity sku-id

• device_version from the command get_version --board.

Instead of implementing a new probe function, we can reuse the existing shell function, which executes a single command, and writes a probe statement like:

{
  "eval": {
    "sequence": {
      "functions": [
        {
          "shell": {
            "command": "cros_config /identity sku-id",
            "key": "device_sku"
          }
        },
        {
          "shell": {
            "command": "get_version --board",
            "key": "device_version"
          }
        }
      ]
    }
  }
}

The expected probed results is:

[
  {
    "device_sku": <output_of_the_cros_config_command>,
    "device_version": <output_of_the_get_version_command>
  }
]

As this function is very common to use, the probe framework also supplies a syntax sugar for it. Above probe statement can be simplified to:

{
  "eval": [  # A list of functions means to apply the `sequence`
             # function.
    {
      "shell": {
        "command": "cros_config /identity sku-id",
        "key": "device_sku"
      }
    },
    {
      "shell": {
        "command": "get_version --board",
        "key": "device_version"
      }
    }
  ]
}