Process ordering

[gnufied]

Implement support for adding index to processes such that they can be started in specific order.

[gnufied]

@iffyuva can you have a look?

[iffyuva]

@gnufied i looked at this PR today morning, and PR looks good. only concern is backward compatibility. let me try out this branch for couple of projects, and i will let you know. thanks.

[gnufied]

I think it should be 100% backward compatible, the only change that users not using this feature will see is - 1s delay between starting their processes. I added that because, sometimes when processes are dependent - it is a good idea to introduce some delay between starting them. But we can probably drop it too.

[nisanthchunduru]

Just curious. Can two processes have the same index?

[postgres]
directory = /Users/nisanth/code/SupportBee-Rails
command = /Users/nisanth/.pgvm/environments/current/bin/postgres -D /usr/local/var/postgres
index = 1

[redis]
directory = /Users/nisanth/builds/redis-2.4.2/src
command = ./redis-server /usr/local/etc/redis.conf
index = 1

[rails]
directory = /Users/nisanth/code/SupportBee-Rails
; Depends on redis and postgres
command = bundle exec rails s
index = 2

[gnufied]

Yeah they can, in which case they would be ordered by order in which they were parsed. In fact if a process has to no index, currently it is assigned 0 index.

[gnufied]

It may be worth assigning higher index for processes without explicit index, rather than 0. @nisanth074 what you think?

[nisanthchunduru]

@gnufied If I add a process which doesn't depend on anything else

[postgres]
directory = /Users/nisanth/code/SupportBee-Rails
command = /Users/nisanth/.pgvm/environments/current/bin/postgres -D /usr/local/var/postgres
index = 1

[redis]
directory = /Users/nisanth/builds/redis-2.4.2/src
command = ./redis-server /usr/local/etc/redis.conf
index = 1

[rails]
directory = /Users/nisanth/code/SupportBee-Rails
; Depends on redis and postgres
command = bundle exec rails s
index = 2

[faye]
directory = /Users/nisanth/code/SupportBee-Rails
; We used to use faye for push events
; I'd intuitively expect faye to be started immediately
command = bundle exec faye

I'd intuitively expect the process to be started immediately. Hence I feel defaulting to 0 index for processes without explicit index is fine.

[iffyuva]

couple of things to discuss:

• index can be implicit, ie order in which processes appear in ini file is the order in which we can assign an index, and start processes
• should invoker list show index of process?