#ifndef __XRDSSISCALE_HH__ #define __XRDSSISCALE_HH__ /******************************************************************************/ /* */ /* X r d S s i S c a l e . h h */ /* */ /* (c) 2013 by the Board of Trustees of the Leland Stanford, Jr., University */ /* Produced by Andrew Hanushevsky for Stanford University under contract */ /* DE-AC02-76-SFO0515 with the Department of Energy */ /* */ /* This file is part of the XRootD software suite. */ /* */ /* XRootD is free software: you can redistribute it and/or modify it under */ /* the terms of the GNU Lesser General Public License as published by the */ /* Free Software Foundation, either version 3 of the License, or (at your */ /* option) any later version. */ /* */ /* XRootD is distributed in the hope that it will be useful, but WITHOUT */ /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */ /* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */ /* License for more details. */ /* */ /* You should have received a copy of the GNU Lesser General Public License */ /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */ /* COPYING (GPL license). If not, see . */ /* */ /* The copyright holder's institutional names and contributor's names may not */ /* be used to endorse or promote products derived from this software without */ /* specific prior written permission of the institution or contributor. */ /******************************************************************************/ #include #include "XrdSys/XrdSysPthread.hh" class XrdSsiScale { public: static const int maxSprd =256; static const int maxEnt = 32; // Must be power of two static const int entShft = 8; // Allows a spread of 256 static const unsigned int maxPend = 65500; int getEnt() {entMutex.Lock(); if (pendCnt[nowEnt] < maxPend) {pendCnt[nowEnt]++; if (maxSpread) return Spread(nowEnt); entMutex.UnLock(); return nowEnt << entShft; } int xEnt = (nowEnt < maxEnt ? nowEnt+1 : 0); int zEnt = maxEnt; do {for (int i = xEnt; i < zEnt; i++) {if (pendCnt[i] < maxPend) {pendCnt[i]++; nowEnt = i; if (maxSpread) return Spread(i); entMutex.UnLock(); return i; } } if (!xEnt) break; xEnt = 0; zEnt = nowEnt; } while(true); entMutex.UnLock(); return -1; } void retEnt(int xEnt) {xEnt >>= entShft; if (xEnt >= 0 && xEnt < maxEnt) {entMutex.Lock(); if (pendCnt[xEnt]) pendCnt[xEnt]--; entMutex.UnLock(); } } bool rsvEnt(int xEnt) {xEnt >>= entShft; if (xEnt < 0 && xEnt >= maxEnt) return false; entMutex.Lock(); if (pendCnt[nowEnt] < maxPend) {pendCnt[nowEnt]++; entMutex.UnLock(); return true; } entMutex.UnLock(); return false; } void setSpread(short sval) {if (sval <= 0) maxSpread = 0; else if (sval < maxSprd) maxSpread = sval; else maxSpread = maxSprd; } XrdSsiScale() : nowEnt(0), maxSpread(4), nowSpread(0) {memset(pendCnt, 0, sizeof(uint16_t)*maxEnt);} ~XrdSsiScale() {} private: int Spread(int ent) // Called with entMutex locked and return unlocked. {int n = nowSpread; nowSpread++; if (nowSpread >= maxSpread) nowSpread = 0; entMutex.UnLock(); return (ent << entShft) | n; } XrdSysMutex entMutex; uint16_t pendCnt[maxEnt]; int nowEnt; short maxSpread; short nowSpread; }; #endif