From b34c3eee2bf5cb05a6f47c0ed9e318632c8dc534 Mon Sep 17 00:00:00 2001
From: Luke Gorrie <luke@snabb.co>
Date: Mon, 22 Feb 2016 13:06:18 +0000
Subject: [PATCH] engine: Set shm path to "app/$name"

Set the shared memory path (shm.path) to a private namespace for each
app with prefix "app/$name".

This means that apps can create shm objects such as counters and by
default these will appear in a local namespace for that app.
---
 src/core/app.lua | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/core/app.lua b/src/core/app.lua
index 35a5305631..099fc3125a 100644
--- a/src/core/app.lua
+++ b/src/core/app.lua
@@ -5,6 +5,7 @@ local lib     = require("core.lib")
 local link    = require("core.link")
 local config  = require("core.config")
 local timer   = require("core.timer")
+local shm     = require("core.shm")
 local counter = require("core.counter")
 local zone    = require("jit.zone")
 local ffi     = require("ffi")
@@ -65,6 +66,8 @@ end
 -- Run app:methodname() in protected mode (pcall). If it throws an
 -- error app will be marked as dead and restarted eventually.
 local function with_restart (app, method)
+   local oldshm = shm.path
+   shm.path = app.shmpath
    if use_restart then
       -- Run fn in protected mode using pcall.
       local status, err = pcall(method, app)
@@ -75,6 +78,7 @@ local function with_restart (app, method)
    else
       method(app)
    end
+   shm.path = oldshm
 end
 
 -- Restart dead apps.
@@ -162,7 +166,11 @@ function apply_config_actions (actions, conf)
    function ops.start (name)
       local class = conf.apps[name].class
       local arg = conf.apps[name].arg
+      local shmpath, shmorig = "app/"..name, shm.path
+      shm.path = shmpath
       local app = class:new(arg)
+      shm.path = shmorig
+      local shmpath = "app/"..name
       if type(app) ~= 'table' then
          error(("bad return value from app '%s' start() method: %s"):format(
                   name, tostring(app)))
@@ -171,6 +179,7 @@ function apply_config_actions (actions, conf)
       app.appname = name
       app.output = {}
       app.input = {}
+      app.shmpath = shmpath
       new_app_table[name] = app
       table.insert(new_app_array, app)
       app_name_to_index[name] = #new_app_array