Class: ClickhouseRuby::ConnectionPool

Inherits:
Object
  • Object
show all
Defined in:
lib/clickhouse_ruby/connection_pool.rb

Overview

Thread-safe connection pool for managing multiple ClickHouse connections

Features:

  • Thread-safe checkout/checkin with mutex

  • Configurable pool size and timeout

  • Automatic health checks before returning connections

  • with_connection block pattern for safe usage

  • Idle connection cleanup

Examples:

Basic usage with block (recommended)

pool = ClickhouseRuby::ConnectionPool.new(config)
pool.with_connection do |conn|
  response = conn.post('/query', 'SELECT 1')
end

Manual checkout/checkin (use with caution)

conn = pool.checkout
begin
  response = conn.post('/query', 'SELECT 1')
ensure
  pool.checkin(conn)
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config, size: nil, timeout: nil) ⇒ ConnectionPool

Creates a new connection pool

Parameters:

  • config (Configuration) —

    connection configuration

  • size (Integer) (defaults to: nil) —

    maximum pool size (default from config)

  • timeout (Integer) (defaults to: nil) —

    wait timeout in seconds (default from config)



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 42

def initialize(config, size: nil, timeout: nil)
  @config = config
  @size = size || config.pool_size
  @timeout = timeout || config.pool_timeout
  @connection_options = config.to_connection_options

  # Pool state
  @available = []           # Connections available for checkout
  @in_use = []             # Connections currently checked out
  @all_connections = []    # All connections ever created

  # Synchronization
  @mutex = Mutex.new
  @condition = ConditionVariable.new

  # Stats
  @total_checkouts = 0
  @total_timeouts = 0
  @created_at = Time.now
end

Instance Attribute Details

#size ⇒ Integer (readonly)

Returns maximum number of connections in the pool.

Returns:

  • (Integer) —

    maximum number of connections in the pool



32
33
34
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 32

def size
  @size
end

#timeout ⇒ Integer (readonly)

Returns timeout in seconds when waiting for a connection.

Returns:

  • (Integer) —

    timeout in seconds when waiting for a connection



35
36
37
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 35

def timeout
  @timeout
end

Instance Method Details

#available_count ⇒ Integer

Returns the number of currently available connections

Returns:

  • (Integer) 


150
151
152
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 150

def available_count
  @mutex.synchronize { @available.size }
end

#checkin(connection) ⇒ void

This method returns an undefined value.

Returns a connection to the pool

Parameters:

  • connection (Connection) —

    the connection to return



128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 128

def checkin(connection)
  return unless connection

  @mutex.synchronize do
    @in_use.delete(connection)

    # Only return healthy connections to the available pool
    if connection.healthy? && !connection.stale?
      @available << connection
    else
      # Disconnect unhealthy connections
      connection.disconnect rescue nil
      @all_connections.delete(connection)
    end

    @condition.signal
  end
end

#checkout ⇒ Connection

Checks out a connection from the pool

If no connections are available and the pool is at capacity, waits up to @timeout seconds for one to become available.

Returns:

Raises:



89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 89

def checkout
  deadline = Time.now + @timeout

  @mutex.synchronize do
    loop do
      # Try to get an available connection
      if (conn = get_available_connection)
        @in_use << conn
        @total_checkouts += 1
        return conn
      end

      # Try to create a new connection if under capacity
      if @all_connections.size < @size
        conn = create_connection
        @in_use << conn
        @total_checkouts += 1
        return conn
      end

      # Wait for a connection to be returned
      remaining = deadline - Time.now
      if remaining <= 0
        @total_timeouts += 1
        raise PoolTimeout.new(
          "Could not obtain a connection from the pool within #{@timeout} seconds " \
          "(pool size: #{@size}, in use: #{@in_use.size})"
        )
      end

      @condition.wait(@mutex, remaining)
    end
  end
end

#cleanup(max_idle_seconds = 300) ⇒ Integer

Removes idle/unhealthy connections from the pool

Parameters:

  • max_idle_seconds (Integer) (defaults to: 300) —

    maximum idle time before removal

Returns:

  • (Integer) —

    number of connections removed



198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 198

def cleanup(max_idle_seconds = 300)
  removed = 0

  @mutex.synchronize do
    @available.reject! do |conn|
      if conn.stale?(max_idle_seconds) || !conn.healthy?
        conn.disconnect rescue nil
        @all_connections.delete(conn)
        removed += 1
        true
      else
        false
      end
    end
  end

  removed
end

#exhausted? ⇒ Boolean

Checks if all connections are currently in use

Returns:

  • (Boolean) 


171
172
173
174
175
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 171

def exhausted?
  @mutex.synchronize do
    @available.empty? && @all_connections.size >= @size
  end
end

#health_check ⇒ Hash

Pings all available connections to check health

Returns:

  • (Hash) —

    status report



220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 220

def health_check
  @mutex.synchronize do
    healthy = 0
    unhealthy = 0

    @available.each do |conn|
      if conn.ping
        healthy += 1
      else
        unhealthy += 1
      end
    end

    {
      available: @available.size,
      in_use: @in_use.size,
      total: @all_connections.size,
      capacity: @size,
      healthy: healthy,
      unhealthy: unhealthy
    }
  end
end

#in_use_count ⇒ Integer

Returns the number of connections currently in use

Returns:

  • (Integer) 


157
158
159
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 157

def in_use_count
  @mutex.synchronize { @in_use.size }
end

#inspect ⇒ String

Returns a string representation of the pool

Returns:

  • (String) 


264
265
266
267
268
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 264

def inspect
  @mutex.synchronize do
    "#<#{self.class.name} size=#{@size} available=#{@available.size} in_use=#{@in_use.size}>"
  end
end

#shutdown ⇒ void

This method returns an undefined value.

Closes all connections and resets the pool

This should be called when shutting down the application.



182
183
184
185
186
187
188
189
190
191
192
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 182

def shutdown
  @mutex.synchronize do
    (@available + @in_use).each do |conn|
      conn.disconnect rescue nil
    end

    @available.clear
    @in_use.clear
    @all_connections.clear
  end
end

#stats ⇒ Hash

Returns pool statistics

Returns:

  • (Hash) —

    pool statistics



247
248
249
250
251
252
253
254
255
256
257
258
259
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 247

def stats
  @mutex.synchronize do
    {
      size: @size,
      available: @available.size,
      in_use: @in_use.size,
      total_connections: @all_connections.size,
      total_checkouts: @total_checkouts,
      total_timeouts: @total_timeouts,
      uptime_seconds: Time.now - @created_at
    }
  end
end

#total_count ⇒ Integer

Returns the total number of connections (available + in use)

Returns:

  • (Integer) 


164
165
166
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 164

def total_count
  @mutex.synchronize { @all_connections.size }
end

#with_connection {|Connection| ... } ⇒ Object

Executes a block with a checked-out connection

This is the recommended way to use the pool. The connection is automatically returned to the pool when the block completes, even if an exception is raised.

Yields:

Returns:

  • (Object) —

    the block’s return value

Raises:



72
73
74
75
76
77
78
79
 
# File 'lib/clickhouse_ruby/connection_pool.rb', line 72

def with_connection
  conn = checkout
  begin
    yield conn
  ensure
    checkin(conn)
  end
end