From fb085aeb4ebc0bbf609fee747fc3930b51d9f00c Mon Sep 17 00:00:00 2001
From: rick olson <technoweenie@gmail.com>
Date: Wed, 13 Nov 2019 11:09:53 -0700
Subject: [PATCH 1/2] Set middleware_mutex when middleware/adapter classes are
 defined

---
 lib/faraday/adapter.rb             | 1 +
 lib/faraday/middleware.rb          | 6 ++++++
 lib/faraday/middleware_registry.rb | 8 +++++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/faraday/adapter.rb b/lib/faraday/adapter.rb
index 407c2367f..535ecb514 100644
--- a/lib/faraday/adapter.rb
+++ b/lib/faraday/adapter.rb
@@ -33,6 +33,7 @@ def supports_parallel?
 
       def inherited(subclass)
         super
+        subclass.middleware_mutex
         subclass.supports_parallel = supports_parallel?
       end
     end
diff --git a/lib/faraday/middleware.rb b/lib/faraday/middleware.rb
index 5bbe4a0e1..03c44bf50 100644
--- a/lib/faraday/middleware.rb
+++ b/lib/faraday/middleware.rb
@@ -17,5 +17,11 @@ def close
         warn "#{@app} does not implement \#close!"
       end
     end
+
+    def self.inherited(subclass)
+      super
+      subclass.send(:load_error=, load_error) # DependencyLoader.inherited
+      subclass.middleware_mutex
+    end
   end
 end
diff --git a/lib/faraday/middleware_registry.rb b/lib/faraday/middleware_registry.rb
index 021038fec..692d0a0cf 100644
--- a/lib/faraday/middleware_registry.rb
+++ b/lib/faraday/middleware_registry.rb
@@ -6,6 +6,11 @@ module Faraday
   # Adds the ability for other modules to register and lookup
   # middleware classes.
   module MiddlewareRegistry
+    def self.extended(klass)
+      super
+      klass.middleware_mutex
+    end
+
     # Register middleware class(es) on the current module.
     #
     # @param autoload_path [String] Middleware autoload path
@@ -92,8 +97,9 @@ def lookup_middleware(key)
     end
 
     def middleware_mutex(&block)
+      puts "#{self}: middleware_mutex" if @middleware_mutex.nil?
       @middleware_mutex ||= Monitor.new
-      @middleware_mutex.synchronize(&block)
+      @middleware_mutex.synchronize(&block) if block
     end
 
     def fetch_middleware(key)

From 25ed0656f4286879be22c2e2d661edad63d7a5db Mon Sep 17 00:00:00 2001
From: Olle Jonsson <olle.jonsson@gmail.com>
Date: Fri, 27 Mar 2020 22:39:07 +0100
Subject: [PATCH 2/2] Dedicate a method to initialize middleware mutex

---
 lib/faraday/adapter.rb             | 2 +-
 lib/faraday/middleware.rb          | 2 +-
 lib/faraday/middleware_registry.rb | 9 ++++++---
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/lib/faraday/adapter.rb b/lib/faraday/adapter.rb
index 535ecb514..565c49027 100644
--- a/lib/faraday/adapter.rb
+++ b/lib/faraday/adapter.rb
@@ -33,7 +33,7 @@ def supports_parallel?
 
       def inherited(subclass)
         super
-        subclass.middleware_mutex
+        subclass.init_mutex
         subclass.supports_parallel = supports_parallel?
       end
     end
diff --git a/lib/faraday/middleware.rb b/lib/faraday/middleware.rb
index 03c44bf50..6400bc913 100644
--- a/lib/faraday/middleware.rb
+++ b/lib/faraday/middleware.rb
@@ -21,7 +21,7 @@ def close
     def self.inherited(subclass)
       super
       subclass.send(:load_error=, load_error) # DependencyLoader.inherited
-      subclass.middleware_mutex
+      subclass.init_mutex
     end
   end
 end
diff --git a/lib/faraday/middleware_registry.rb b/lib/faraday/middleware_registry.rb
index 692d0a0cf..5fefaffd5 100644
--- a/lib/faraday/middleware_registry.rb
+++ b/lib/faraday/middleware_registry.rb
@@ -8,7 +8,7 @@ module Faraday
   module MiddlewareRegistry
     def self.extended(klass)
       super
-      klass.middleware_mutex
+      klass.init_mutex
     end
 
     # Register middleware class(es) on the current module.
@@ -96,10 +96,13 @@ def lookup_middleware(key)
         raise(Faraday::Error, "#{key.inspect} is not registered on #{self}")
     end
 
+    def init_mutex
+      @middleware_mutex = Monitor.new
+    end
+
     def middleware_mutex(&block)
       puts "#{self}: middleware_mutex" if @middleware_mutex.nil?
-      @middleware_mutex ||= Monitor.new
-      @middleware_mutex.synchronize(&block) if block
+      @middleware_mutex.synchronize(&block)
     end
 
     def fetch_middleware(key)