1、JNI 里有兩個特殊的函數 JNI_OnLoad和 JNI_OnUnload,它們分別在加載和卸載庫的時候 被調用。 JNI_OnLoad在調用其他任何方法之前被執行,而且能夠很方便地用于初始化在這 一進程的生命周期中沒有發生變化的變量,并用于協調 JNI 規范的版本。在默認情況下,庫 會測量它自己的進程的參數,但是通過調用 systemInformation.setPid (方法它可以從 Java 應用程序被重載。 s_PID C 變量用來保存 PID ,而 s_currentProcess用來保存進程句柄(用于 Windows 的是 HANDLE 類型,而用于 Solaris 的是 int

2、 類型 。為了讀取的一些參數,應該首 先打開進程句柄,我們需要在庫關閉使用的時候停止同一個進程句柄(通常它在 JVM 因為 相同的原因而關閉的時候發生 。這就是 JNI_OnUnload(函數起作用的地方。但是, JVM 的一些實現事實上沒有調用 JNI_OnUnload( ,還有發生句柄會永遠打開的危險。為了降低 這種可能性,我們應該在 Java 應用程序里加入一個明確調用 detachProcess ( C 函數的關 閉掛鉤。下面就是我們加入關閉掛鉤的方法:if (pid!=-1 int result = SystemInformation.setPid(pid;if (result!=0

3、 return;hasPid = true;/ Create shutdown hook for proper process detachRuntime.getRuntime(.addShutdownHook(new Thread( public void run( SystemInformation.detachProcess(;通過調用 WinAPI 里的 GetSystemInfo ( ,我們還可以獲得關于中央處理器的一些信息。只 要它是 CPU 的占用率根據這個值來調節,測量進程最重要的值就是處理器的個數 (s_numberOfProcessors 。 SystemInformati

4、on.getSysInfo (的 Win32實現相當麻煩,因為 在各個版本的 Windows 里,關于操作系統的版本、補丁、服務包以及相關硬件等信息被以 不同的方式保存。 所以需要讀者來分析相關的源代碼和代碼中的注釋。 下面就是 Windows XP上代碼輸出的示例:System.out.println("SysInfo: ”+SystemInformation.getSysInfo(:SysInfo: WinXP Professional Service Pack 1 (Build 2600,And the same code on Solaris will give:SysInf

5、o: SunOS 5.8 sxav-dev Generic_108528-29 sun4u sparcSUNW,Ultra-Enterprise Sun_Microsystems為了獲得 CPU 上進程所占用的總時間,我們使用了 WinAPI 的函數 GetProcessTimes. 其他的 函數實現都非常簡單,直接調用 WinAPI ,所以沒有什么必要討論它們。列表 D 里是用于 Windows 版本的 GCC 的 make.bat 文件,用來幫助讀者創建相關的。 dll 庫。列表 Dgcc -D_JNI_IMPLEMENTATION_ -Wl , kill-at -IC :/jdk1.3.

6、1_12/include -IC : /jdk1.3.1_12/include/win32 -shared C : /cpu_profile/src/native/com_vladium_utils_SystemInformation.c -o C:/cpu_profile/dll/silib.dll C: /MinGW/lib/libpsapi.a 這個庫的 Solaris 實現見列表 E 和列表 F. 這兩個都是 C 語言文件, 應該 被編譯到一個共享庫 (.so 里。 用于編譯共享庫的幫助器 make.sh 見列表 G. 所有基于 Solaris 系統的調用被移到列表 F 里,這使得列表

7、 E 就是一個 JNI 的簡單包裝程序。 Solaris 實現要比 Win32實現更加復雜, 要求更多的臨時數據結構、 內核和進程表。列出的代碼里有更多的注 釋。列表 E/* - */* class.* This is a ported version from Win32 to Solaris.* For simplicity, this implementaion assumes JNI 1.2+ and omits error handling.*/* - */#include#include "com_vladium_utils_SystemInformation.h&quo

8、t;/ Helper Solaris8-dependent external routinesextern int sol_getCPUs(;extern int sol_getFreeMem(;extern int sol_getMaxMem(;extern long int sol_getProcessCPUTime(int pid,int nproc;extern double sol_getProcessCPUPercentage(int pid;extern long sol_getMemoryUsage(int pid;extern long sol_getMemoryReside

9、nt(int pid;extern char* sol_getSysInfo(;extern void initKVM(;static jint s_PID;static int s_numberOfProcessors;static int externalCPUmon;static int alreadyDetached;/* - */* . */* This method was added in JNI 1.2. It is executed once before any other * methods are called and is ostensibly for negotia

10、ting JNI spec versions, but * can also be conveniently used for initializing variables that will not* change throughout the lifetime of this process.*/JNIEXPORT jint JNICALLJNI_OnLoad (JavaVM * vm, void * reserveds_PID = _getpid (;externalCPUmon = 0;alreadyDetached = 0;/* use kstat to update all pro

11、cessor information */s_numberOfProcessors = sol_getCPUs(;initKVM(;return JNI_VERSION_1_2;/* . */* Class: com_vladium_utils_SystemInformation* Method: getCPUs* Signature: (I*/JNIEXPORT jint JNICALLJava_com_vladium_utils_SystemInformation_getCPUs (JNIEnv * env, jclass cls return (jints_numberOfProcess

12、ors;/* . */* Class: com_vladium_utils_SystemInformation* Method: getSysInfo* Signature: (S*/JNIEXPORT jstring JNICALLJava_com_vladium_utils_SystemInformation_getSysInfo (JNIEnv * env, jclass cls char * buf = sol_getSysInfo(;jstring retval = (*env->NewStringUTF(env,buf;free(buf;return retval;/* .

13、*/* Class: com_vladium_utils_SystemInformation* Method: getProcessID* Signature: (I*/JNIEXPORT jint JNICALLJava_com_vladium_utils_SystemInformation_getProcessID (JNIEnv * env, jclass cls return s_PID;/* . */* Class: com_vladium_utils_SystemInformation* Method: setPid* Signature: (I*/JNIEXPORT jint J

14、NICALLJava_com_vladium_utils_SystemInformation_setPid (JNIEnv * env, jclass cls, jint pid s_PID = pid;externalCPUmon = 1;printf("CPUmon Attached to process."fflush(stdout;return 0;/* . */* Class: com_vladium_utils_SystemInformation* Method: detachProcess* Signature: (I*/JNIEXPORT jint JNIC

15、ALLJava_com_vladium_utils_SystemInformation_detachProcess (JNIEnv * env, jclass cls if (externalCPUmon && !alreadyDetached alreadyDetached = 1;printf("CPUmon Detached from process."fflush(stdout;return 0;/* . */* Class: com_vladium_utils_SystemInformation* Method: getProcessCPUTime

16、* Signature: (J*/JNIEXPORT jlong JNICALLJava_com_vladium_utils_SystemInformation_getProcessCPUTime (JNIEnv * env, jclass cls return (jlongsol_getProcessCPUTime(ints_PID,s_numberOfProcessors;/* . */* Class: com_vladium_utils_SystemInformation* Method: getMaxMem* Signature: (J*/JNIEXPORT jlong JNICALL

17、Java_com_vladium_utils_SystemInformation_getMaxMem (JNIEnv * env, jclass cls return (jlongsol_getMaxMem(;/* . */* Class: com_vladium_utils_SystemInformation* Method: getFreeMem* Signature: (J*/JNIEXPORT jlong JNICALLJava_com_vladium_utils_SystemInformation_getFreeMem (JNIEnv * env, jclass clsreturn

18、(jlongsol_getFreeMem(;/* . */* define min elapsed time (in units of 10E-7 sec: */#define MIN_ELAPSED_TIME (10000/* Class: com_vladium_utils_SystemInformation* Method: getProcessCPUUsage* Signature: (D*/JNIEXPORT jdouble JNICALLJava_com_vladium_utils_SystemInformation_getProcessCPUUsage (JNIEnv * env

19、, jclass cls return 0.0;/* . */* Class: com_vladium_utils_SystemInformation* Method: getProcessCPUPercentage* Signature: (D*/JNIEXPORT jdouble JNICALLJava_com_vladium_utils_SystemInformation_getProcessCPUPercentage (JNIEnv * env, jclass cls return (jdoublesol_getProcessCPUPercentage(ints_PID;/* . */

20、* Class: com_vladium_utils_SystemInformation* Method: getMemoryUsage* Signature: (J*/JNIEXPORT jlong JNICALLJava_com_vladium_utils_SystemInformation_getMemoryUsage (JNIEnv * env, jclass cls return (jlongsol_getMemoryUsage(ints_PID;/* . */* Class: com_vladium_utils_SystemInformation* Method: getMemor

21、yResident* Signature: (J*/JNIEXPORT jlong JNICALLJava_com_vladium_utils_SystemInformation_getMemoryResident (JNIEnv * env, jclass cls return (jlongsol_getMemoryResident(ints_PID;#undef MIN_ELAPSED_TIME/* - */* end of file */列表 F/* - */* Solaris-dependent system routines and kernel calls* Used for ge

22、tting memory and CPU consumption statistics*/* - */#include# ifndef KSTAT_DATA_UINT32# define ui32 ul# endif#include#include#include#include#include#include#include#include#define _STRUCTURED_PROC 1#include#define prpsinfo psinfo#define pr_fill pr_nlwp#define ZOMBIE(p (p->pr_nlwp = 0#define SIZE_

23、K(p (p->pr_size#define RSS_K(p (p->pr_rssize#define PROCFS "/proc"/* definitions for indices in the nlist array */#define X_V 0#define X_MPID 1#define X_ANONINFO 2#define X_MAXMEM 3#define X_SWAPFS_MINFREE 4#define X_FREEMEM 5#define X_AVAILRMEM 6#define X_AVENRUN 7#define X_CPU 8#de

24、fine X_NPROC 9#define X_NCPUS 10static struct nlist nlst =, /* 0 */ /* replaced by dynamic allocation */, /* 1 */#if OSREV >= 56/* this structure really has some extra fields, but the first three match */ , /* 2 */#else, /* 2 */#endif, /* 3 */ /* use sysconf */, /* 4 */ /* used only w/ USE_ANONIN

25、FO */, /* 5 */ /* available from kstat >= 2.5 */, /* 6 */ /* available from kstat >= 2.5 */, /* 7 */ /* available from kstat */, /* 8 */ /* available from kstat */, /* 9 */ /* available from kstat */, /* 10 */ /* available from kstat */;static kstat_ctl_t *kc = NULL;static kstat_t *cpu_ks;stat

26、ic cpu_stat_t *cpu_stat;static int ncpus;kvm_t *kd;static unsigned long freemem_offset;static unsigned long maxmem_offset;static unsigned long freemem = -1L;static unsigned long maxmem = -1L;/* pagetok function is really a pointer to an appropriate function */ static int pageshift;static int (*p_pag

27、etok (;#define pagetok(size (*p_pagetok(sizeint pagetok_none(int size return(size;int pagetok_left(int size return(size << pageshift;int pagetok_right(int size return(size >> pageshift;#define UPDKCID(nk,okif (nk = -1 perror("kstat_read "exit(1;if (nk != okgoto kcid_changed;voi

28、d initKVM( int i;/* perform the kvm_open - suppress error here */kd = kvm_open (NULL, NULL, NULL, O_RDONLY, NULL;/* calculate pageshift value */i = sysconf(_SC_PAGESIZE;pageshift = 0;while (i >>= 1 > 0pageshift+;/* calculate an amount to shift to K values */* remember that log base 2 of 102

29、4 is 10 (i.e.: 210 = 1024 */ pageshift -= 10;/* now determine which pageshift function is appropriate for the result (have to because x << y is undefined for y < 0 */ if (pageshift > 0/* this is the most likely */p_pagetok = pagetok_left;else if (pageshift = 0p_pagetok = pagetok_none;els

30、ep_pagetok = pagetok_right;pageshift = -pageshift;#define SI_LEN 512#define BUFSIZE 256char * sol_getSysInfo( char * retbuf = (char*malloc(SI_LEN;int curend = 0;int maxl = SI_LEN;*retbuf=0;char * buf = (char*malloc(BUFSIZE; long res = sysinfo(SI_SYSNAME,buf,BUFSIZE; if (res>0 && res<=m

31、axl strcat(retbuf,buf;curend=res-1;maxl=SI_LEN-curend;if (curend0 && res<=maxl strcat(retbuf,buf;curend+=res-1;maxl=SI_LEN-curend;if (curend0 && res<=maxl strcat(retbuf,buf;curend+=res-1;maxl=SI_LEN-curend;if (curend0 && res<=maxl strcat(retbuf,buf; curend+=res-1;max

32、l=SI_LEN-curend; if (curend0 && res<=maxl strcat(retbuf,buf; curend+=res-1;maxl=SI_LEN-curend; if (curend0 && res<=maxl strcat(retbuf,buf; curend+=res-1;maxl=SI_LEN-curend; if (curend0 && res<=maxl strcat(retbuf,buf; curend+=res-1;maxl=SI_LEN-curend; if (curend0 &

33、;& res<=maxl strcat(retbuf,buf; curend+=res-1;maxl=SI_LEN-curend; if (curendvalue.ui32 > ncpus ncpus = kn->value.ui32;cpu_ks = (kstat_t * realloc (cpu_ks, ncpus * sizeof (kstat_t *; cpu_stat = (cpu_stat_t * realloc (cpu_stat,ncpus * sizeof (cpu_stat_t;for (ks = kc->kc_chain; ks;ks =

34、ks->ks_nextif (strncmp(ks->ks_name, "cpu_stat", 8 = 0nkcid = kstat_read(kc, ks, NULL;/* if kcid changed, pointer might be invalid */UPDKCID(nkcid, kcid;cpu_ksncpu = ks;ncpu+;if (ncpu > ncpusfprintf(stderr, "kstat finds too many cpus: should be %d ",ncpus;exit(1;/* note t

35、hat ncpu could be less than ncpus, but that's okay */ changed = 0;/* return the number of cpus found */ncpus=ncpu;return ncpu;unsigned long sol_getMaxMem( maxmem = pagetok(sysconf(_SC_PHYS_PAGES;return maxmem;unsigned long sol_getFreeMem( kstat_t *ks;kstat_named_t *kn;ks = kstat_lookup(kc, "

36、;unix", 0, "system_pages"if (kstat_read(kc, ks, 0 = -1 perror("kstat_read"exit(1;if (kd != NULL /* always get freemem from kvm if we can*/(void getkval (freemem_offset, (int * (&freemem, sizeof (freemem, "freemem" else kn = kstat_data_lookup(ks, "freemem&q

37、uot;if (knfreemem = kn->value.ul;return (unsigned longpagetok(freemem;/ Returns the number of milliseconds (not nanoseconds and seconds elapsed on processor / since process start. The returned value is adjusted for the number of processors in the system. long int sol_getProcessCPUTime(int pid,int

38、 nproc struct prpsinfo currproc;int fd;char buf30;long int retval=0;snprintf(buf, sizeof(buf, "%s/%d/psinfo", PROCFS, pid;if (fd = open (buf, O_RDONLY < 0 return 0L;if (read(fd, &currproc, sizeof(psinfo_t != sizeof(psinfo_t (voidclose(fd;return 0L;(voidclose(fd;retval = (currproc.pr

39、_time.tv_sec * 1000 + currproc.pr_time.tv_nsec / 1000000 / nproc;return retval;/ Returns percentage CPU by pid/ In Solaris 8 it is contained in procfsdouble sol_getProcessCPUPercentage(int pid struct prpsinfo currproc;int fd;char buf30;double retval=0.0;snprintf(buf, sizeof(buf, "%s/%d/psinfo&q

40、uot;, PROCFS, pid;if (fd = open (buf, O_RDONLY < 0 return 0;if (read(fd, &currproc, sizeof(psinfo_t != sizeof(psinfo_t (voidclose(fd;return 0;(voidclose(fd;retval = (doublecurrproc.pr_pctcpu/0x8000*100;return retval;/ Returns current space allocated for the process, in bytes. Those pages may

41、or may not be in memory.long sol_getMemoryUsage(int pid struct prpsinfo currproc;int fd;char buf30;double retval=0.0;snprintf(buf, sizeof(buf, "%s/%d/psinfo", PROCFS, pid;if (fd = open (buf, O_RDONLY < 0 return 0;if (read(fd, &currproc, sizeof(psinfo_t != sizeof(psinfo_t (voidclose(

42、fd;return 0;(voidclose(fd;retval = currproc.pr_size;return retval;/ Returns current process space being resident in memory.long sol_getMemoryResident(int pid struct prpsinfo currproc;int fd;char buf30;double retval=0.0;snprintf(buf, sizeof(buf, "%s/%d/psinfo", PROCFS, pid;if (fd = open (buf, O_RDONLY < 0 return 0;if (rea