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Active Record 连接池队列

线程安全、公平、LIFO 队列。旨在与 ConnectionPool 一起使用,后者与它共享一个监视器。

方法
A
C
D
N
P

类公共方法

new(lock = Monitor.new)

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 14
def initialize(lock = Monitor.new)
  @lock = lock
  @cond = @lock.new_cond
  @num_waiting = 0
  @queue = []
end

实例公共方法

add(element)

element 添加到队列中。从不阻塞。

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 37
def add(element)
  synchronize do
    @queue.push element
    @cond.signal
  end
end

any_waiting?()

测试当前是否有任何线程正在等待队列。

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 22
def any_waiting?
  synchronize do
    @num_waiting > 0
  end
end

clear()

从队列中移除所有元素。

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 52
def clear
  synchronize do
    @queue.clear
  end
end

delete(element)

如果队列中存在 element,则将其移除并返回,否则返回 nil

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 45
def delete(element)
  synchronize do
    @queue.delete(element)
  end
end

num_waiting()

返回当前在此队列上等待的线程数。

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 30
def num_waiting
  synchronize do
    @num_waiting
  end
end

poll(timeout = nil)

移除队列的头部。

如果未提供 timeout,则在可用元素数严格大于当前等待的线程数时移除并返回队列的头部(即,不要插队)。否则,返回 nil

如果提供了 timeout,则在没有可用元素时阻塞,等待最多 timeout 秒,直到有元素可用。

引发

timeout 秒内可用,

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 72
def poll(timeout = nil)
  synchronize { internal_poll(timeout) }
end