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Adds more resiliency to retrying read operations during failures. #685

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Adds more resiliency to retrying read operations during failures. #685

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a2a7e0f
Adds more resiliency to retrying read operations during failures.
jonhyman Sep 1, 2015
86053b8
Retry reads when deserializing a reply.
jonhyman Sep 3, 2015
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10 changes: 10 additions & 0 deletions lib/mongo/retryable.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,10 @@ module Retryable
# @since 2.1.0
NOT_MASTER = 'not master'.freeze

# Error codes received around reconfiguration
CONNECTION_ERRORS_RECONFIGURATION_CODES = [ 15988, 10276, 11600, 9001, 13639, 10009, 11002, 7 ].map(&:to_s).freeze
CONNECTION_ERRORS_MAGIC_STRINGS = [ 'could not get last error', 'connection attempt failed' ].freeze

# Execute a read operation with a retry.
#
# @example Execute the read.
Expand All @@ -43,6 +47,12 @@ def read_with_retry(&block)
block.call
rescue Error::SocketError, Error::SocketTimeoutError
retry_operation(&block)
rescue Error::OperationFailure => e
if CONNECTION_ERRORS_RECONFIGURATION_CODES.any? {|code| e.message.include?(code) } || CONNECTION_ERRORS_MAGIC_STRINGS.any? {|str| e.message.include?(str)}
retry_operation(&block)
else
raise e
end
end
end

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8 changes: 7 additions & 1 deletion lib/mongo/server/connectable.rb
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Expand Up @@ -20,6 +20,10 @@ class Server
# @since 2.0.0
module Connectable

def self.included(base)
base.__send__(:include, Mongo::Retryable)
end

# The ssl option prefix.
#
# @since 2.1.0
Expand Down Expand Up @@ -103,7 +107,9 @@ def ensure_same_process!
end

def read
ensure_connected{ |socket| Protocol::Reply.deserialize(socket) }
read_with_retry do
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This will not work here as the connection does not know anything about the cluster and the retry code calls cluster.scan!.

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Hm. Thoughts on how to handle a retry if the read that ultimately gets called from here gets a socket error, then?

Stack trace again:

from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/socket.rb:123:in `block in read'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/socket.rb:191:in `handle_errors'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/socket.rb:122:in `read'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/protocol/serializers.rb:62:in `deserialize'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/protocol/message.rb:193:in `deserialize_header'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/protocol/message.rb:83:in `deserialize'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connectable.rb:106:in `block in read'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connectable.rb:91:in `ensure_connected'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connectable.rb:106:in `read'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connection.rb:180:in `deliver'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connection.rb:125:in `block in dispatch'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/monitoring/publishable.rb:47:in `publish_command'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/server/connection.rb:124:in `dispatch'
  from /var/www/bundle/ruby/2.2.0/bundler/gems/mongo-ruby-driver-a2a7e0f949a3/lib/mongo/operation/executable.rb:36:in `block in execute'

ensure_connected{ |socket| Protocol::Reply.deserialize(socket) }
end
end
end
end
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52 changes: 52 additions & 0 deletions spec/mongo/retryable_spec.rb
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Expand Up @@ -66,6 +66,58 @@ def write
end
end

context 'when an operation error occurs that could not get last error' do

before do
expect(operation).to receive(:execute).and_raise(Mongo::Error::OperationFailure.new("could not get last error")).ordered
expect(cluster).to receive(:scan!).and_return(true).ordered
expect(operation).to receive(:execute).and_return(true).ordered
end

it 'executes the operation twice' do
expect(retryable.read).to be true
end
end

context 'when an operation error occurs that had a connection attempt failed' do

before do
expect(operation).to receive(:execute).and_raise(Mongo::Error::OperationFailure.new("connection attempt failed")).ordered
expect(cluster).to receive(:scan!).and_return(true).ordered
expect(operation).to receive(:execute).and_return(true).ordered
end

it 'executes the operation twice' do
expect(retryable.read).to be true
end
end

context 'when an operation error occurs with code 15988' do

before do
expect(operation).to receive(:execute).and_raise(Mongo::Error::OperationFailure.new("error querying server (15988)")).ordered
expect(cluster).to receive(:scan!).and_return(true).ordered
expect(operation).to receive(:execute).and_return(true).ordered
end

it 'executes the operation twice' do
expect(retryable.read).to be true
end
end

context 'when an operation error occurs with code 13639' do

before do
expect(operation).to receive(:execute).and_raise(Mongo::Error::OperationFailure.new("connection attempt failed (13639)")).ordered
expect(cluster).to receive(:scan!).and_return(true).ordered
expect(operation).to receive(:execute).and_return(true).ordered
end

it 'executes the operation twice' do
expect(retryable.read).to be true
end
end

context 'when a socket timeout error occurs' do

before do
Expand Down