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finished readme

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Jordan Orelli 8 years ago
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README.md
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@ -60,15 +60,16 @@ The other lines in this comment, that is, the lines that do _not_ begin with
project, that is just one line: the line that includes `procmon.h`, the header project, that is just one line: the line that includes `procmon.h`, the header
file for the C code that we want to access. file for the C code that we want to access.
Down [in the Go program's `main` function](procmon.go#L50), we spawn a goroutine to listen on a Down [in the Go program's `main` function](procmon.go#L50), we spawn a
channel for changes: goroutine to listen on a channel for changes:
```go ```go
go reportChanges() go reportChanges()
``` ```
The `reportChanges` function simply reads values off of a channel and prints [The `reportChanges`
them: function](https://github.com/jordanorelli/procmon/blob/master/procmon.go#L38-L47)
simply reads values off of a channel and prints them:
```go ```go
func reportChanges() { func reportChanges() {
@ -106,12 +107,12 @@ void MonitorProcesses() {
} }
``` ```
This function does two things: it starts by accessing a singleton of our This function does two things: it starts by accessing a singleton of [our
Objective-C class `ProcWatcher` (that's `[ProcWatcher shared]`, which is defined Objective-C class `ProcWatcher`](ProcWatcher.m#L4) (that's `[ProcWatcher
[here](ProcWatcher.m#L6)) and shared]`, which is defined [here](ProcWatcher.m#L6)) and invoking [its
invoking its `startWatching` method. This subscribes our `ProcWatcher` instance `startWatching` method](ProcWatcher.m#L16). This subscribes our `ProcWatcher`
to OS notifications. We'll come back to how the ProcWatcher subscribes to instance to OS notifications. We'll come back to how the ProcWatcher subscribes
events in a bit. to events in a bit.
#### sidebar: the Run Loop #### sidebar: the Run Loop
@ -135,11 +136,9 @@ returns in the Go program, the Go runtime ends the process, which is _not_ what
we want. So this call gives us two things: it sets up the notification system we want. So this call gives us two things: it sets up the notification system
infrastructure, and it prevents our program from terminating. infrastructure, and it prevents our program from terminating.
#### back to observing NSNotifications #### end sidebar: back to observing NSNotifications
[The `startWatching` [The `startWatching` method](ProcWatcher.m#L16) accesses the current OSX user's
method](ProcWatcher.m#L6)
accesses the current OSX user's
[`NSWorkspace`](https://developer.apple.com/reference/appkit/nsworkspace). The [`NSWorkspace`](https://developer.apple.com/reference/appkit/nsworkspace). The
`NSWorkspace` handle allows us to hook into `NSWorkspace` handle allows us to hook into
[`NSNotificationCenter`](https://developer.apple.com/reference/foundation/nsnotificationcenter) [`NSNotificationCenter`](https://developer.apple.com/reference/foundation/nsnotificationcenter)
@ -190,7 +189,7 @@ bridging code in C that can be imported by our own C code. This allows our own
C code to call back into the Go program and invoke Go functions. cgo will C code to call back into the Go program and invoke Go functions. cgo will
silently generate this C header file behind the scenes. That C header file, silently generate this C header file behind the scenes. That C header file,
which is given the totally obvious and well-documented name `_cgo_export.h` is which is given the totally obvious and well-documented name `_cgo_export.h` is
generated when you run `go build` by cgo, used to help compile our C code, and generated by cgo when you run `go build`, used to help compile our C code, and
then deleted. You won't notice it getting written and deleted because it goes then deleted. You won't notice it getting written and deleted because it goes
by so quickly, but it's there, and it's on disk when our C code gets compiled. by so quickly, but it's there, and it's on disk when our C code gets compiled.
In order to access those definitions from our C code, our C code has to import In order to access those definitions from our C code, our C code has to import
@ -229,7 +228,19 @@ typedef GoInt64 GoInt;
typedef long long GoInt64; typedef long long GoInt64;
``` ```
That intermediate type is generated automatically by cgo in the intermediate
header file `_cgo_export.h` (before deleting it). If you want to look at this
file as a reference to see what is visible to your C code, you can manually
invoke cgo with `go tool cgo ...`, passing in the files to be processed by cgo.
You shouldn't need to do this in the normal case, but it can be useful for
debugging.
Anyway, calling that C function invokes the corresponding Go function Anyway, calling that C function invokes the corresponding Go function
`AppStarted`, which writes a value onto a channel. That value is read off of `AppStarted`, which writes a value onto a channel. That value is read off of
the channel by our `reportChanges` goroutine and used to print out the name of the channel by our `reportChanges` goroutine and used to print out the name of
the App that had been launched or terminated by the user. the App that had been launched or terminated by the user.
Feel free to run the project on OSX. After running it, you should get no output
and your terminal should be under procmon's control. Open _another_ OSX app and
you should see a line like `started: com.apple.Notes` (if you start Notes.app,
for example). If you don't ... pull requests welcome ;)

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