mirror of
https://github.com/codeninjasllc/discourse.git
synced 2024-11-23 15:48:43 -05:00
Second attempt which removes any kind proxying.
This commit is contained in:
Guo Xiang Tan
parent
46589a1a0c
commit
0058d09e35
3 changed files with 72 additions and 128 deletions
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@ -1,13 +1,7 @@
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development:
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prepared_statements: false
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adapter: postgresql_fallback
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host: 172.17.0.2
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port: 6432
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adapter: postgresql
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database: discourse_development
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username: tgxworld
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password: test
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replica_host: 172.17.0.3
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replica_port: 6432
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min_messages: warning
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pool: 5
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timeout: 5000
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@ -28,15 +28,21 @@ end
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module ActiveRecord
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module ConnectionHandling
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def postgresql_fallback_connection(config)
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master_connection = postgresql_connection(config)
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replica_connection = postgresql_connection(config.dup.merge({
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host: config[:replica_host], port: config[:replica_port]
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begin
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connection = postgresql_connection(config)
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rescue PG::ConnectionBad => e
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connection = postgresql_connection(config.dup.merge({
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"host" => config["replica_host"], "port" => config["replica_port"]
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}))
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verify_replica(replica_connection)
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klass = ConnectionAdapters::PostgreSQLFallbackAdapter.proxy_pass(master_connection.class)
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klass.new(master_connection, replica_connection, logger, config)
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verify_replica(connection)
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Discourse.enable_readonly_mode if !Discourse.readonly_mode?
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start_connection_heartbeart(connection, config)
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end
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connection
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end
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private
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@ -45,84 +51,17 @@ module ActiveRecord
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value = connection.raw_connection.exec("SELECT pg_is_in_recovery()").values[0][0]
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raise "Replica database server is not in recovery mode." if value == 'f'
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end
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def interval
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5
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end
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module ConnectionAdapters
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class PostgreSQLFallbackAdapter < AbstractAdapter
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ADAPTER_NAME = "PostgreSQLFallback".freeze
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MAX_FAILURE = 5
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HEARTBEAT_INTERVAL = 5
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attr_reader :main_connection
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def self.all_methods(klass)
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methods = []
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(klass.ancestors - AbstractAdapter.ancestors).each do |_klass|
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%w(public protected private).map do |level|
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methods << _klass.send("#{level}_instance_methods", false)
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end
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end
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methods.flatten.uniq.sort
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end
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def self.proxy_pass(klass)
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Class.new(self) do
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(self.all_methods(klass) - self.all_methods(self)).each do |method|
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self.class_eval <<-EOF
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def #{method}(*args, &block)
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proxy_method(:#{method}, *args, &block)
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end
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EOF
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end
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end
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end
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def initialize(master_connection, replica_connection, logger, config)
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super(nil, logger, config)
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@master_connection = master_connection
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@main_connection = @master_connection
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@replica_connection = replica_connection
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@failure_count = 0
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load!
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end
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def proxy_method(method, *args, &block)
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@main_connection.send(method, *args, &block)
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rescue ActiveRecord::StatementInvalid => e
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if e.message.include?("PG::UnableToSend") && @main_connection == @master_connection
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@failure_count += 1
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if @failure_count == MAX_FAILURE
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Discourse.enable_readonly_mode if !Discourse.readonly_mode?
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@main_connection = @replica_connection
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load!
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connection_heartbeart(@master_connection)
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@failure_count = 0
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else
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proxy_method(method, *args, &block)
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end
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end
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raise e
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end
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private
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def load!
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@visitor = @main_connection.visitor
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@connection = @main_connection.raw_connection
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end
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def connection_heartbeart(connection, interval = HEARTBEAT_INTERVAL)
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def start_connection_heartbeart(existing_connection, config)
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timer_task = Concurrent::TimerTask.new(execution_interval: interval) do |task|
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connection.reconnect!
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connection = postgresql_connection(config)
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if connection.active?
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@main_connection = connection
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load!
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existing_connection.disconnect!
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Discourse.disable_readonly_mode if Discourse.readonly_mode?
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task.shutdown
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end
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@ -133,4 +72,3 @@ module ActiveRecord
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end
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end
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end
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end
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@ -1,55 +1,67 @@
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require 'rails_helper'
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require_dependency 'active_record/connection_adapters/postgresql_fallback_adapter'
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describe ActiveRecord::ConnectionAdapters::PostgreSQLFallbackAdapter do
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let(:master_connection) { ActiveRecord::Base.connection }
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let(:replica_connection) { master_connection.dup }
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let(:adapter) { described_class.new(master_connection, replica_connection, nil, nil) }
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before :each do
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ActiveRecord::Base.clear_all_connections!
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end
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describe "proxy_method" do
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context "when master connection is not active" do
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before do
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replica_connection.stubs(:send)
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master_connection.stubs(:send).raises(ActiveRecord::StatementInvalid.new('PG::UnableToSend'))
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master_connection.stubs(:reconnect!)
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master_connection.stubs(:active?).returns(false)
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@old_const = described_class::HEARTBEAT_INTERVAL
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described_class.const_set("HEARTBEAT_INTERVAL", 0.1)
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describe ActiveRecord::ConnectionHandling do
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let(:config) do
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ActiveRecord::Base.configurations["test"].merge({
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"adapter" => "postgresql_fallback",
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"replica_host" => "localhost",
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"replica_port" => "6432"
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})
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end
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after do
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ActiveRecord::Base.clear_all_connections!
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Discourse.disable_readonly_mode
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described_class.const_set("HEARTBEAT_INTERVAL", @old_const)
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end
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it "should set site to readonly mode and carry out failover and switch back procedures" do
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expect(adapter.main_connection).to eq(master_connection)
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adapter.proxy_method('some method')
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expect(Discourse.readonly_mode?).to eq(true)
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expect(adapter.main_connection).to eq(replica_connection)
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describe "#postgresql_fallback_connection" do
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it 'should return a PostgreSQL adapter' do
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expect(ActiveRecord::Base.postgresql_fallback_connection(config))
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.to be_an_instance_of(ActiveRecord::ConnectionAdapters::PostgreSQLAdapter)
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end
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master_connection.stubs(:active?).returns(true)
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context 'when master server is down' do
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before do
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@replica_connection = mock('replica_connection')
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ActiveRecord::Base.expects(:postgresql_connection).with(config).raises(PG::ConnectionBad)
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ActiveRecord::Base.expects(:postgresql_connection).with(config.merge({
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"host" => "localhost", "port" => "6432"
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})).returns(@replica_connection)
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ActiveRecord::Base.expects(:verify_replica).with(@replica_connection)
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@replica_connection.expects(:disconnect!)
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ActiveRecord::Base.stubs(:interval).returns(0.1)
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Concurrent::TimerTask.any_instance.expects(:shutdown)
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end
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it 'should failover to a replica server' do
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ActiveRecord::Base.postgresql_fallback_connection(config)
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expect(Discourse.readonly_mode?).to eq(true)
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ActiveRecord::Base.unstub(:postgresql_connection)
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sleep 0.15
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expect(Discourse.readonly_mode?).to eq(false)
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expect(adapter.main_connection).to eq(master_connection)
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expect(ActiveRecord::Base.connection)
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.to be_an_instance_of(ActiveRecord::ConnectionAdapters::PostgreSQLAdapter)
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end
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end
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it 'should raise errors not related to the database connection' do
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master_connection.stubs(:send).raises(StandardError.new)
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expect { adapter.proxy_method('some method') }.to raise_error(StandardError)
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end
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context 'when both master and replica server is down' do
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it 'should raise the right error' do
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ActiveRecord::Base.expects(:postgresql_connection).raises(PG::ConnectionBad).twice
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it 'should proxy methods successfully' do
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expect(adapter.proxy_method(:execute, 'SELECT 1').values[0][0]).to eq("1")
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expect(adapter.proxy_method(:active?)).to eq(true)
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expect(adapter.proxy_method(:raw_connection)).to eq(master_connection.raw_connection)
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expect { ActiveRecord::Base.postgresql_fallback_connection(config) }
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.to raise_error(PG::ConnectionBad)
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end
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end
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end
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end
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