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Merge pull request #6425 from pinetops/resolver_concurrency_fix
Resolver concurrency fix
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tenderlove committed May 21, 2012
2 parents 513a052 + 719b008 commit 254c042
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Showing 2 changed files with 72 additions and 23 deletions.
87 changes: 68 additions & 19 deletions actionpack/lib/action_view/template/resolver.rb
Expand Up @@ -2,6 +2,7 @@
require "active_support/core_ext/class"
require "active_support/core_ext/class/attribute_accessors"
require "action_view/template"
require "thread"

module ActionView
# = Action View Resolver
Expand All @@ -24,6 +25,64 @@ def initialize(name, prefix, partial, virtual)
end
end

# Threadsafe template cache
class Cache #:nodoc:
class CacheEntry
attr_accessor :templates

delegate :synchronize, :to => "@mutex"

def initialize
@mutex = Mutex.new
end
end

def initialize
@data = Hash.new { |h1,k1| h1[k1] = Hash.new { |h2,k2|
h2[k2] = Hash.new { |h3,k3| h3[k3] = Hash.new { |h4,k4| h4[k4] = {} } } } }
@mutex = Mutex.new
end

# Cache the templates returned by the block
def cache(key, name, prefix, partial, locals)
cache_entry = nil

# first obtain a lock on the main data structure to create the cache entry
@mutex.synchronize do
cache_entry = @data[key][name][prefix][partial][locals] ||= CacheEntry.new
end

# then to avoid a long lasting global lock, obtain a more granular lock
# on the CacheEntry itself
cache_entry.synchronize do
if Resolver.caching?
# all templates are cached forever the first time they are accessed
cache_entry.templates ||= yield
else
# templates are still cached, but are only returned if they are
# all still current
fresh = yield

mtime = cache_entry.templates && cache_entry.templates.map(&:updated_at).max

newer = !mtime || fresh.empty? || fresh.any? { |t| t.updated_at > mtime }

if newer
cache_entry.templates = fresh
else
cache_entry.templates
end
end
end
end

def clear
@mutex.synchronize do
@data.clear
end
end
end

cattr_accessor :caching
self.caching = true

Expand All @@ -32,12 +91,11 @@ class << self
end

def initialize
@cached = Hash.new { |h1,k1| h1[k1] = Hash.new { |h2,k2|
h2[k2] = Hash.new { |h3,k3| h3[k3] = Hash.new { |h4,k4| h4[k4] = {} } } } }
@cache = Cache.new
end

def clear_cache
@cached.clear
@cache.clear
end

# Normalizes the arguments and passes it on to find_template.
Expand Down Expand Up @@ -65,27 +123,18 @@ def build_path(name, prefix, partial)

# Handles templates caching. If a key is given and caching is on
# always check the cache before hitting the resolver. Otherwise,
# it always hits the resolver but check if the resolver is fresher
# before returning it.
# it always hits the resolver but if the key is present, check if the
# resolver is fresher before returning it.
def cached(key, path_info, details, locals) #:nodoc:
name, prefix, partial = path_info
locals = locals.map { |x| x.to_s }.sort!

if key && caching?
@cached[key][name][prefix][partial][locals] ||= decorate(yield, path_info, details, locals)
else
fresh = decorate(yield, path_info, details, locals)
return fresh unless key

scope = @cached[key][name][prefix][partial]
cache = scope[locals]
mtime = cache && cache.map(&:updated_at).max

if !mtime || fresh.empty? || fresh.any? { |t| t.updated_at > mtime }
scope[locals] = fresh
else
cache
if key
@cache.cache(key, name, prefix, partial, locals) do
decorate(yield, path_info, details, locals)
end
else
decorate(yield, path_info, details, locals)
end
end

Expand Down
8 changes: 4 additions & 4 deletions actionpack/test/template/lookup_context_test.rb
Expand Up @@ -169,7 +169,7 @@ def teardown

assert_not_equal template, old_template
end

test "responds to #prefixes" do
assert_equal [], @lookup_context.prefixes
@lookup_context.prefixes = ["foo"]
Expand All @@ -180,7 +180,7 @@ def teardown
class LookupContextWithFalseCaching < ActiveSupport::TestCase
def setup
@resolver = ActionView::FixtureResolver.new("test/_foo.erb" => ["Foo", Time.utc(2000)])
@resolver.stubs(:caching?).returns(false)
ActionView::Resolver.stubs(:caching?).returns(false)
@lookup_context = ActionView::LookupContext.new(@resolver, {})
end

Expand Down Expand Up @@ -247,6 +247,6 @@ def setup
@lookup_context.view_paths.find("foo", "parent", true, details)
end
assert_match %r{Missing partial parent/foo with .* Searched in:\n \* "/Path/to/views"\n}, e.message
end
end

end

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