以下这段伪代码来自于

的

，这段代码并不长但基本对获取latch、spin、sleep的行为都描述清楚了，如果你对latch仍不甚了了，那么这段代码会对你很有帮助:      

Function Get_Latch(latch_name,mode){  If Mode eq ‘immediate’ {    If Fast_Get(latch_name) {      return TRUE    Else {      return FALSE    }  }  Else {    If Fast_Get(latch_name)    Then {      v$latch.gets++      return TRUE    }    Else {      v$latch.misses++      for try = 0 .. large_number      {        if Spin_Get(latch_name)        Then {          return TRUE        }        Else {          T0 = time          Sleep(try)          T1=time          Register_Event("latch free",T1-T0)        }      } -- spin/sleep loop    }  }}Function Fast_Get(latch_name){  If try_to_get_latch(latch_name)  Then {    return TRUE  }  Else {    return FALSE  }}Function Spin_Get(latch_name){  v$latch.spin_get++  for i = 1 to _spin_count  {    If Fast_Get(latch_name)    Then {      return TRUE    }  }}Function Sleep(try){  v$latch.sleeps++  v$latch.sleep[try]++  sleeptime =    decode(try,0,0,1,10,2,20,3,~40,4,~80,...~2000)  sleep(sleeptime)}