status-go/geth/jail/doc.go

64 lines
2.4 KiB
Go

/*
Package jail implements "jailed" enviroment for executing arbitrary
JavaScript code using Otto JS interpreter (https://github.com/robertkrimen/otto).
Jail create multiple JailCells, one cell per status client chat. Each cell runs own
Otto virtual machine and lives forever, but that may change in the future.
+----------------------------------------------+
| Jail |
+----------------------------------------------+
+---------+ +---------+ +---------+ +---------+
| Cell | | Cell | | Cell | | Cell |
|ChatID 1 | |ChatID 2 | |ChatID 3 | |ChatID N |
|+-------+| |+-------+| |+-------+| |+-------+|
||Otto VM|| ||Otto VM|| ||Otto VM|| ||Otto VM||
|+-------+| |+-------+| |+-------+| |+-------+|
|| Loop || || Loop || || Loop || || Loop ||
++-------++ ++-------++ ++-------++ ++-------++
Get and Set
(*JailCell).Get/Set functions provide transparent and concurrently safe wrappers for
Otto VM Get and Set functions respectively. See Otto documentation for usage examples:
https://godoc.org/github.com/robertkrimen/otto
Call and Run
(*JailCell).Call/Run functions allows executing arbitrary JS in the cell. They're also
wrappers arount Otto VM functions of the same name. Run accepts raw JS strings for execution,
Call takes a JS function name (defined in VM) and parameters.
Timeouts and intervals support
Default Otto VM interpreter doesn't support setTimeout()/setInterval() JS functions,
because they're not part of ECMA-262 spec, but properties of the window object in browser.
We add support for them using http://github.com/deoxxa/ottoext/timers and http://github.com/deoxxa/ottoext/loop
packages.
Each cell starts a new loop in a separate goroutine, registers functions for setTimeout/setInterval
calls and associate them with this loop. All JS code executed as callback to setTimeout/setInterval
will be handled by this loop.
For example, following code:
cell.Run(`setTimeout(function(){ value = "42" }, 2000);`)
will execute setTimeout and return immidiately, but callback function will
be executed after 2 seconds in the loop that was started upon current cell.
In order to capture response one may use following approach:
err = cell.Set("__captureResponse", func(val string) otto.Value {
fmt.Println("Captured response from callback:", val)
return otto.UndefinedValue()
})
cell.Run(`setTimeout(function(){ __captureResponse("OK") }, 2000);`)
Fetch support
TBD
*/
package jail