Make ClimateControl.modify re-entrant #24
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houndci-bot
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Jan 24, 2017
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| expect(foo).to eq('bar') |
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| it "is re-entrant" do | ||
| foo = with_modified_env(FOO: 'foo') do | ||
| with_modified_env(BAR: 'bar') do | ||
| 'bar' |
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| expect(ENV["BAZ"]).to be_nil | |||
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| it "is re-entrant" do | |||
| foo = with_modified_env(FOO: 'foo') do | |||
| with_modified_env(BAR: 'bar') do | |||
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| @@ -111,6 +111,16 @@ | |||
| expect(ENV["BAZ"]).to be_nil | |||
| end | |||
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| it "is re-entrant" do | |||
| foo = with_modified_env(FOO: 'foo') do | |||
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krallin
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With the lock added in 0.4, it's no longer safe to nest calls
`ClimateControl.modify`, which is actually a useful feature when e.g.
using `ClimateControl` in RSpec `around { ... }` blocks. Doing so
results in a deadlock (stack trace from the spec included in this
commit):
```
1) Climate control is re-entrant
Failure/Error: ClimateControl.modify(options, &block)
ThreadError:
deadlock; recursive locking
# ./lib/climate_control/modifier.rb:10:in `process'
# ./lib/climate_control.rb:10:in `modify'
# ./spec/acceptance/climate_control_spec.rb:131:in `with_modified_env'
# ./spec/acceptance/climate_control_spec.rb:116:in `block (3 levels) in <top (required)>'
# ./lib/climate_control/modifier.rb:31:in `call'
# ./lib/climate_control/modifier.rb:31:in `run_block'
# ./lib/climate_control/modifier.rb:13:in `block in process'
# ./lib/climate_control/modifier.rb:10:in `process'
# ./lib/climate_control.rb:10:in `modify'
# ./spec/acceptance/climate_control_spec.rb:131:in `with_modified_env'
# ./spec/acceptance/climate_control_spec.rb:115:in `block (2 levels) in <top (required)>'
# ./spec/acceptance/climate_control_spec.rb:149:in `block (2 levels) in <top (required)>'
```
Since the lock is here to protect against different threads accessing
ClimateControl at the same time, it's safe for a given thread to make
any changes it wants to the environment as long as it holds the locks,
which is what this patch does.
krallin
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@krallin This looks great. I did some testing on my own as well. Thanks for your contribution! |
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With the lock added in 0.4, it's no longer safe to nest calls
ClimateControl.modify, which is actually a useful feature when e.g.using
ClimateControlin RSpecaround { ... }blocks. Doing soresults in a deadlock (stack trace from the spec included in this
commit):
Since the lock is here to protect against different threads accessing
ClimateControl at the same time, it's safe for a given thread to make
any changes it wants to the environment as long as it holds the locks,
which is what this patch does.
There was a bit of discussion about re-entrancy in #11, but I don't think the fact that
ClimateControlwill deadlock when nesting calls in the absence of re-entrancy was addressed.Thanks!