How to copy EMS datastore for interDC transport? Ought to be _fast_.

#ifndef _GNU_SOURCE
#define _GNU_SOURCE 
#endif
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <malloc.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <pthread.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/sendfile.h>
#include <errno.h>
#include <time.h>
#include <sys/syscall.h>
#include <inttypes.h>
#ifdef AIO_VIA_SYSCALL
#include <linux/aio_abi.h>
#else
#include <libaio.h>
#endif
#include <list>

#define SYSOUTF(msg, params...) do { char buff[1024]; memset(buff, 0, 1024); snprintf(buff, 1024, msg, params); write(1,buff,strlen(buff)); } while(0)
#define SYSOUT(msg) write(1, msg, strlen(msg))

#define ONE_MB (1024*1024)
#define ONE_GB (1024L*ONE_MB)

#define STRATEGY_MMAP_WRITE  0
#define STRATEGY_MMAP_BOTH   1
#define STRATEGY_SERIAL      2
#define STRATEGY_SENDFILE    3
#define STRATEGY_AIO         4

static const char* STRATEGY_DESC[] = { "MMAP+WRITE", "MMAPx2+MEMCPY", "READ+WRITE", "SENDFILE", "AIO" };

static struct timespec __ts, __ts_res;
static clockid_t __clock = CLOCK_REALTIME;

static int strategy = STRATEGY_MMAP_WRITE;
static int fd_in = -1, fd_out = -1, err_in = 0, err_out = 0;
static void *addr = NULL, *addr2 = NULL;
static long size_in = 0, blk_size = 0;
static int warn_mem_params_not_optimal = 1;

#define TIMER_START() do { timer_start(&__ts,__clock); } while(0)
#define TIMER_STOP() do { timer_stop(&__ts,__clock); clock_getres(__clock,&__ts_res); } while(0)
#define PRINT_WALL_TIME() do { long msec = __ts.tv_nsec/1000000L; SYSOUTF("[INFO] WALL TIME: %ldsec %ldmsec %ldusec +- %ldnsec\n",(long)__ts.tv_sec,msec,(__ts.tv_nsec - msec*1000000L)/1000L,__ts_res.tv_nsec); } while(0)

static inline int timer_start(struct timespec *ts, clockid_t clid) {
    int res = clock_gettime(clid,ts);
 if (res!=0) {
  int e = errno;
  SYSOUTF("Failed timer_start due to '%s'\r\n", strerror(e));
 }
    return res;
}

static inline int timer_stop(struct timespec *ts, clockid_t clid) {
    struct timespec ts1;
    int res = clock_gettime(clid,&ts1);
    if (res!=0) {
        int e = errno;
        SYSOUTF("Failed timer_stop due to '%s'\r\n", strerror(e));
  return res;
    }
    ts->tv_sec = ts1.tv_sec - ts->tv_sec;
    ts->tv_nsec = ts1.tv_nsec - ts->tv_nsec;
    if (ts->tv_nsec < 0) {
  ts->tv_nsec += 1000000000L;
        ts->tv_sec--;
    }
    return 0;
}

long get_rmem_limit() {
    struct rlimit rlimit;
    int res = getrlimit(RLIMIT_MEMLOCK, &rlimit);
    if (res == 0) {
  return (long)rlimit.rlim_max;
    }
    return -1L;
}

int open_source_file(char *path) {
    int res = -1;
    int extra_flags = strategy == STRATEGY_AIO ? O_DIRECT : 0;
    do {
  res = open(path, O_LARGEFILE | O_RDONLY | extra_flags);
    }
    while (res == -1 && errno == EINTR);    
    return res;
}

int open_dest_file(char *path) {
    int res = -1;
    int extra_flags = strategy == STRATEGY_AIO ? O_DIRECT : 0;
    do {
  res = open(path, O_CREAT | O_LARGEFILE | O_RDWR | extra_flags, 0666);
    }
    while (res == -1 && errno == EINTR);
    return res;
}

long get_file_size(int fd, long *block_size) {
    struct stat stat;
    TIMER_START();
    int res = fstat(fd, &stat);
    if (res == 0) {
  if (block_size != NULL)
   *block_size = stat.st_blksize;
  return stat.st_size;
    }
    return -1L;
}

int allocate_file(int fd, long size) {
    return fallocate(fd, 0, 0, size);
}

void preload_file_advise(int fd, long size, off_t base_offset) {
 int res = posix_fadvise(fd, base_offset, size, POSIX_FADV_WILLNEED | POSIX_FADV_SEQUENTIAL);
 if (res != 0) {
  int e = errno;
  SYSOUTF("[WARN] POSIX fadvise returned error '%s'\r\n", strerror(e));
 }
}

void* mmap_file(int fd, long size, int mode, off_t base_offset = 0) {
    preload_file_advise(fd, size, base_offset);
    int PERF_FLAGS[] = { MAP_HUGETLB | MAP_LOCKED, MAP_HUGETLB, MAP_LOCKED, 0 };
    void *addr = NULL;
    int i = 0;
    for (; i < 4; i++) {
  addr = mmap(NULL, size, mode == 0 ? PROT_READ : PROT_WRITE, MAP_SHARED | MAP_POPULATE | PERF_FLAGS[i], fd, base_offset);
  if (addr!= (void*)-1)
   break;
    }
    if (addr == (void*)-1)
  return NULL;
    if (i!=0 && warn_mem_params_not_optimal) {
  SYSOUT("[WARN] Memory access is not optimal (no huge TLB & pages locked into RAM)\r\n");
  warn_mem_params_not_optimal = 0;
    }
    int res = posix_madvise(addr, size, POSIX_MADV_WILLNEED | POSIX_MADV_SEQUENTIAL);
    if (res != 0) {
  int e = errno;
  SYSOUTF("[WARN] POSIX madvise returned error '%s'\r\n", strerror(e));
    }
    res = mlock(addr, size);
    if (res != 0) {
     int e = errno;
     SYSOUTF("[WARN] POSIX mlock returned error '%s'\r\n", strerror(e));
    }
    return addr;
}

int write_file(int fd, void *buff, long len, long base_off = 0) {
    long to_be_written = len;
    long off = 0;
    do {
  long res = pwrite(fd, buff, to_be_written, off + base_off);
  if (res > 0) {
   to_be_written -= res;
   off += res;
   if (to_be_written == 0L)
    break;
  }
  else if (res < 0 && errno != EINTR)
   break;
 }
    while (errno == EINTR);
    TIMER_STOP();
    if (errno == 0)
  fdatasync(fd); 
    return to_be_written == 0 ? 0 : errno;
}    

#define CLEANUP_EXIT(code) { if (addr) munmap(addr, size_in); if (addr2) munmap(addr2, size_in); if (fd_in!=-1) close(fd_in); if (fd_out!=-1) close(fd_out); exit(code); } while(0)
#define CLEANUP_MMAP(size) { if (addr) { munmap(addr, size); addr = NULL; } if (addr2) { munmap(addr2, size); addr2 = NULL; } } while(0)

void open_files(char **argv) {
    long mlock_max = get_rmem_limit();
    SYSOUTF("[INFO] RLIMIT_MEMLOCK is %ldKB,\r\n", mlock_max/1024);
    if (mlock_max < 128*1024*1024) {
  SYSOUTF("[WARN] Please adjust memlock in /etc/security/limits.conf to something big like %d (KB), which is 32GB.\r\n", 32*ONE_MB);
    }
    fd_in = open_source_file(argv[1]); err_in = errno;
    if (fd_in == -1) {
  SYSOUTF("[ERROR] Cannot open source file %s due to error '%s'\r\n", argv[1], strerror(err_in));
  CLEANUP_EXIT(-1);
    }
    fd_out = open_dest_file(argv[2]); err_out = errno;
    if (fd_out == -1) {
  SYSOUTF("[ERROR] Cannot open destination file %s due to error '%s'\r\n", argv[2], strerror(err_out));
  CLEANUP_EXIT(-2);
    }    
    size_in = get_file_size(fd_in, &blk_size); err_in = errno;
    if (size_in == -1L) {
  SYSOUTF("[ERROR] Unable determine file size for %s due to error '%s'\r\n", argv[1], strerror(err_in));
  CLEANUP_EXIT(-3);
    }
    SYSOUTF("[INFO] File size for %s is %ld, block size is %ld.\r\n", argv[1], size_in, blk_size);
    if (allocate_file(fd_out, size_in) != 0) {
  err_out = errno;
  SYSOUTF("[ERROR] Cannot allocate file %s due to error '%s'\r\n", argv[2], strerror(err_out));
  CLEANUP_EXIT(-4);
    }
}

#define MMAP_IN  0
#define MMAP_OUT 1

#ifndef MMAP_CHUNK_SIZE
#define MMAP_CHUNK_SIZE  (128*1024*1024)
#endif

void mmap_copy(char **argv) {
 for (long base = 0; base < size_in; base += MMAP_CHUNK_SIZE) {
  long size = size_in - base;
  if (size > MMAP_CHUNK_SIZE)
   size = MMAP_CHUNK_SIZE;
  else if (size <= 0)
   break;
   
  addr = mmap_file(fd_in, size, MMAP_IN, base);
  if (addr == NULL) {
   err_in = errno;
   SYSOUTF("[ERROR] Cannot load file %s into memory due to error '%s'\r\n", argv[1], strerror(err_in));
   CLEANUP_EXIT(-5);
  }
  if (strategy == STRATEGY_MMAP_WRITE) {
   int res = write_file(fd_out, addr, size, base);
   if (res!=0) {
    SYSOUTF("[ERROR] Could not write file %s due to error '%s'\r\n", argv[2], strerror(res));
    CLEANUP_EXIT(-6);
   }
  }
  else if (strategy == STRATEGY_MMAP_BOTH) {
   addr2 = mmap_file(fd_out, size, MMAP_OUT, base);
   if (addr2 == NULL) {
    err_out = errno;
    SYSOUTF("[ERROR] Cannot load file %s into memory due to error '%s'\r\n", argv[2], strerror(err_out));
    CLEANUP_EXIT(-7);
   }
   else {
    memcpy(addr2, addr, size);
    TIMER_STOP();
    if (msync(addr2, size, MS_SYNC) != 0) {
     err_out = errno;
     SYSOUTF("[ERROR] Cannot sync file %s due to error '%s'\r\n", argv[2], strerror(err_out));
     CLEANUP_EXIT(-8);
    }
   }
  }
  CLEANUP_MMAP(size);
 }
 TIMER_STOP();
}

int sendfile_copy() {
 err_out = 0;
 long to_write = size_in;
 long written_once = 0;
 while (to_write > 0) {
  written_once = sendfile(fd_out, fd_in, NULL, to_write);
  if (written_once == -1) {
   err_out = errno;
   if (err_out != EAGAIN) {
    SYSOUTF("[ERROR] Function sendfile is not supported '%s'\r\n", strerror(err_out));
    return -1;
   }
   else
    continue;
  }
  else {
   to_write -= written_once;
  }
 }
 if (to_write != 0) {
  SYSOUTF("[ERROR] Function sendfile written too small data: %ld vs %ld, error=%s\r\n", size_in - to_write, size_in, strerror(err_out));
  return -1;
 }
 TIMER_STOP();
 return 1;    
}    

#ifndef COPY_BLOCK_SIZE
#define COPY_BLOCK_SIZE 4096
#endif

void serial_copy() {
    char buff[COPY_BLOCK_SIZE];
    long in = 0;
    long out = 0;
    long cnt = 0;
    preload_file_advise(fd_in, size_in, 0);
    do {
  in=read(fd_in, (void*)buff, COPY_BLOCK_SIZE);
  if (in>0) {
   out = in;
   do {
    cnt = write(fd_out, buff, out);
    err_out = errno;
    if (cnt < 0 && err_out != EINTR) {
     SYSOUTF("[ERROR] Broken writing to output file '%s'\r\n", strerror(err_out));
     CLEANUP_EXIT(-10);
    }
    else if (cnt > 0) {
     out -= cnt;
    }
   }
   while (out > 0);
  }
  else {
   if (errno == 0) {
    if (in==0)
     continue;
    else
     break;
   }
   if (errno != EINTR) {
    err_in = errno;
    SYSOUTF("[ERROR] Broken reading of input file '%s'\r\n", strerror(err_in));
    CLEANUP_EXIT(-9); 
   }
   else
    continue;
  }
    }
    while (in > 0); 
 TIMER_STOP();
}

#define PG_SIZE 4096
#define AIO_MAX_NR 1024

#ifdef AIO_VIA_SYSCALL
inline int io_setup(unsigned nr, aio_context_t *ctxp) {
 return syscall(__NR_io_setup, nr, ctxp);
}
inline int io_destroy(aio_context_t ctx) {
 return syscall(__NR_io_destroy, ctx);
}
inline int io_submit(aio_context_t ctx, long nr, struct iocb **cbp) {
 return syscall(__NR_io_submit, nr, cbp);
}
inline int io_cancel(aio_context_t ctx, struct iocb *cb, struct io_event *result) {
 return syscall(__NR_io_cancel, cb, result);
}
inline int io_getevents(aio_context_t ctx, long min_nr, long nr, struct io_event *events, struct timespec *timeout) {
 return syscall(__NR_io_getevents, min_nr, nr, events, timeout);
}
inline void io_prep_pread(struct iocb *cb, int fd, void *buff, long size, long offset) {
 cb->aio_fildes = fd;
 cb->aio_lio_opcode = IOCB_CMD_PREAD;
 cb->aio_buf = (uint64_t)buff;
 cb->aio_offset = offset;
 cb->aio_nbytes = size;
}
#else
#define IOCB_CMD_PREAD  0
#define IOCB_CMD_PWRITE  1
#define IOCB_CMD_FSYNC  2
#define IOCB_CMD_FDSYNC  3
#define IOCB_CMD_NOOP  6
#define aio_context_t io_context_t
#endif

void aio_copy() {
 int chunks = (size_in + (PG_SIZE/2) - 1) / PG_SIZE; /* with padding */
 SYSOUTF("[INFO] AIO copy needs %d chunks\r\n", chunks);
 aio_context_t ctx = 0;
 struct iocb* cbs = (struct iocb*)malloc(AIO_MAX_NR * sizeof(struct iocb));
 struct iocb** cbps = (struct iocb**)malloc(AIO_MAX_NR * sizeof(struct iocb*));
 struct iocb** wcbps = (struct iocb**)malloc(AIO_MAX_NR * sizeof(struct iocb*));
 struct io_event* ioevents = (struct io_event*)malloc(AIO_MAX_NR * sizeof(struct io_event));

 if (cbs==NULL || cbps==NULL || wcbps==NULL || ioevents==NULL) {
  int ret = errno;
  SYSOUTF("[ERROR] Broken malloc '%s'\r\n", strerror(ret));
  CLEANUP_EXIT(-12);
 } 
 
 int ret = io_setup(AIO_MAX_NR, &ctx);
 if (ret < 0) {
  ret = errno;
  SYSOUTF("[ERROR] Broken io_setup for %d chunks '%s'\r\n", chunks, strerror(ret));
  CLEANUP_EXIT(-11); 
 }
 void *bigbuff = malloc(AIO_MAX_NR*PG_SIZE);
#define DELETE_MEM do { if (bigbuff!=NULL) free(bigbuff); free(cbs); free(cbps); free(wcbps); free(ioevents); io_destroy(ctx); } while(0)
 if (bigbuff == NULL) {
  ret = errno;
  SYSOUTF("[ERROR] Buffer allocation failed for input file: '%s'\r\n", strerror(ret));
  DELETE_MEM;
  CLEANUP_EXIT(-12); 
 }
 
 int rounds = (chunks + AIO_MAX_NR/2 - 1) / AIO_MAX_NR; /* with padding */
#define AIO_GROUP_TO_OFFSET(i) (long(i) * PG_SIZE * AIO_MAX_NR)
#define AIO_STEP_TO_OFFSET(i) (long(i) * PG_SIZE)
 for (int i=0; i < AIO_MAX_NR; i++) {
  memset(&cbs[i], 0, sizeof(struct iocb));
  cbps[i] = &cbs[i];
 }

 for (int group=0; group < rounds; group++) {
  int step = 0;
  for (; step < AIO_MAX_NR; step++) {
   long curr_off = AIO_GROUP_TO_OFFSET(group) + AIO_STEP_TO_OFFSET(step);
   long nbytes = size_in - curr_off;
   if (nbytes <= 0) /* we are inside padding */
    break;
   if (nbytes > PG_SIZE)
    nbytes = PG_SIZE;
 
   long pbuff = (long)bigbuff + AIO_STEP_TO_OFFSET(step);
   io_prep_pread(&cbs[step], fd_in, (void*)pbuff, nbytes, curr_off);
  }
  if (step == 0)
   break;
  int todo = io_submit(ctx, step, cbps);
  if (todo != step) {
   ret = errno;
   SYSOUTF("[ERROR] Broken io_submit, group=%d, queued=%d; '%s'\r\n", group, todo >= 0 ? todo : -1, todo < 0 ? strerror(ret) : "failure for given index");
   DELETE_MEM;
   CLEANUP_EXIT(-13); 
  }
  
  int wi = 0;
  while (todo > 0) {
   ret = io_getevents(ctx, 1, todo, ioevents, NULL);
   if (ret < 0) {
    ret = errno;
    SYSOUTF("[ERROR] Broken io_getevents '%s'\r\n", strerror(ret));
    DELETE_MEM;
    CLEANUP_EXIT(-14); 
   }
   else if (ret > 0) {
    todo -= ret;
    int to_write = 0;
    for (int i=0; i < ret; i++) {
     struct iocb *iocbp = (struct iocb*) ioevents[i].obj;
     if (iocbp->aio_lio_opcode == IOCB_CMD_PREAD) {
      iocbp->aio_fildes = fd_out;
      iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
      wcbps[wi++] = iocbp;
      to_write++;
     }
    }
    if (to_write > 0) {
     int e = io_submit(ctx, to_write, &wcbps[wi - to_write]); /* move along linearly */
     if (e != to_write) {
      ret = errno;
      SYSOUTF("[ERROR] Broken io_submit for write '%s'\r\n", e < 0 ? strerror(ret) : "failure for given index");
      DELETE_MEM;
      CLEANUP_EXIT(-15); 
     }  
     else
      todo += to_write;
    }
   }
  }
 }
 DELETE_MEM;
 TIMER_STOP();
}

int main(int argc, char **argv) {

 if (argc < 3) {
  SYSOUTF("Usage: %s SRC_FILE DST_FILE --strategy={mmap,serial,sendfile,aio,default}\r\n", argv[0]);
  return 0;
 }
 if (argc == 4 && strncmp(argv[3], "--strategy=mmap", 15) == 0)
  strategy = STRATEGY_MMAP_BOTH;
 else if (argc == 4 && strncmp(argv[3], "--strategy=serial", 17) == 0)
  strategy = STRATEGY_SERIAL;
 else if (argc == 4 && strncmp(argv[3], "--strategy=sendfile", 19) == 0)
  strategy = STRATEGY_SENDFILE;
 else if (argc == 4 && strncmp(argv[3], "--strategy=aio", 14) == 0)
  strategy = STRATEGY_AIO;
    
 open_files(argv);
 if (strategy == STRATEGY_SERIAL)
  serial_copy();
 else if (strategy == STRATEGY_SENDFILE)
  sendfile_copy();
 else if (strategy == STRATEGY_AIO)
  aio_copy();
 else
  mmap_copy(argv);
    
 SYSOUTF("\r\n[INFO] Success. Strategy was %s\r\n", STRATEGY_DESC[strategy]);
 PRINT_WALL_TIME();
 CLEANUP_EXIT(0);
 return 0;
}

Jak oglądać telewizję gdy niemowlak śpi?

Transmiter Bluetooth Audio (RCA/Jack) podłączony do tunera albo telewizora + słuchawki BT. Urządzenie można zasilać z portu USB telewizora/tunera lub ładowarki do komórki. Gdy transmiter jest podłączony do tunera należy go włączyć i wyciszyć telewizor za pomocą pilota. W przypadku podłączenia do telewizora należy wpiąć w TV kabel Jack, telewizor wyłączy wtedy głośniki. Na zwykłych słuchawkach bez kodeka aptx (wirtualnie wszystkie dostępne na Allegro słuchawki bezprzewodowe robione przez Chińczyków wystawiających towar na alibaba.com) jest lag do 1s, ale można z tym żyć. Porządne słuchawki zapewniające dobrą synchronizację są co najmniej 2 razy droższe. Rozwiązanie jest bardzo fajne, ale ma minus - jest jednoosobowe. Transmiter FM i dwie sztuki słuchawek z radiem mają sporo gorszą jakość dźwięku.

EMS DS tracer

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <pthread.h>
#include <list>

const char interp[] __attribute__((section(".interp"))) = "/lib64/ld-linux-x86-64.so.2";

typedef int (*open_fn)(const char *path, int flags, ...);
typedef ssize_t (*write_fn)(int fd, const void *buf, size_t count);
typedef ssize_t (*writev_fn)(int fd, const struct iovec *iov, int count);
typedef ssize_t (*pwritev_fn)(int fd, const struct iovec *iov, int count, off_t offset);
typedef int (*ftruncate_fn)(int fd, off_t length);

static open_fn _open = NULL;
static open_fn _open64 = NULL;
static write_fn _write = NULL;
static writev_fn _writev = NULL;
static pwritev_fn _pwritev = NULL;
static ftruncate_fn _ftruncate = NULL;
static void *handle_libc = NULL;
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

#define SYSOUTF(msg, params...) do { char buff[1024]; memset(buff, 0, 1024); snprintf(buff, 1024, msg, params); _write(1,buff,strlen(buff)); } while(0)
#define SYSOUT(msg) _write(1, msg, strlen(msg))

void __attribute__((constructor)) __init(void)
{
    if (handle_libc==NULL)
handle_libc = dlopen ("/lib64/libc.so.6", RTLD_NOW);
    if (handle_libc!=NULL) {
_open = (open_fn) dlsym(handle_libc, "open");
_open64 = (open_fn) dlsym(handle_libc, "open64");
_write = (write_fn) dlsym(handle_libc,"write");
_writev = (writev_fn) dlsym(handle_libc,"writev");
_pwritev = (pwritev_fn) dlsym(handle_libc,"pwritev");
_ftruncate = (ftruncate_fn) dlsym(handle_libc, "ftruncate");
SYSOUT("libemscompanion init completed\r\n");
    }
    else {
exit(-1);
    }
}

void __attribute__((destructor)) __fini(void)
{
    if (handle_libc!=NULL)
dlclose(handle_libc);
}

extern "C" {

    int open(const char *path, int flags, ...) {
va_list vargs;
va_start(vargs, flags);
mode_t mode = va_arg(vargs, mode_t);
va_end(vargs);
int ret = _open(path, flags, mode);
SYSOUTF("Open %s = %d\r\n", path, ret);
return ret;
    }
   
    int open64(const char *path, int flags, ...) {
va_list vargs;
va_start(vargs, flags);
mode_t mode = va_arg(vargs, mode_t);
va_end(vargs);
int ret = _open(path, flags, mode);
SYSOUTF("Open %s = %d\r\n", path, ret);
return ret;
    }
   
    ssize_t write(int fd, const void *buf, size_t count) {
off_t curr = lseek(fd, 0, SEEK_CUR);
SYSOUTF("Writing fd = %d, addr = %d, buff = %x, size = %d\r\n", fd, curr, buff, count);
ssize_t ret = _write(fd, buf, count);
return ret;
    }
}

extern "C" void _main(int argc, char **argv) {
    __init();
    SYSOUT("libEMSCompanion 0.0.1\r\n");
    exit(0);
}

EMS File Datastore as a sequential tx log

Writing fd = 9, addr = 24834560, buff = 8c405540, size = 512 (chunk header, const offset, every 1910272 bytes)
Writing fd = 9, addr = 22405120, buff = 8c405710, size = 861696 (full message with headers and body)
Writing fd = 9, addr = 23266816, buff = 8c405710, size = 861696
Writing fd = 9, addr = 26744832, buff = 8c405540, size = 512
Writing fd = 9, addr = 24128512, buff = 8c405710, size = 861696
Writing fd = 9, addr = 24990208, buff = 89c01820, size = 512
Writing fd = 9, addr = 1024, buff = 89c01820, size = 512
Writing fd = 9, addr = 1536, buff = 89c01820, size = 512
Writing fd = 9, addr = 24990720, buff = 89c01820, size = 512 (Client ACK record)
Writing fd = 9, addr = 24991232, buff = 89c01820, size = 512
Writing fd = 9, addr = 24991744, buff = 89c01820, size = 512
Writing fd = 9, addr = 24992256, buff = 89c01820, size = 512
Writing fd = 9, addr = 24992768, buff = 89c01820, size = 512
Writing fd = 9, addr = 24993280, buff = 89c01820, size = 512
Writing fd = 9, addr = 24993792, buff = 89c01820, size = 512
Writing fd = 9, addr = 24994304, buff = 89c01820, size = 512
Writing fd = 9, addr = 24994816, buff = 89c01820, size = 512
Writing fd = 9, addr = 24995328, buff = 89c01820, size = 512
Writing fd = 9, addr = 24995840, buff = 89c01820, size = 512
Writing fd = 9, addr = 24996352, buff = 89c01820, size = 512
Writing fd = 9, addr = 24996864, buff = 89c01820, size = 512
Writing fd = 9, addr = 24997376, buff = 89c01820, size = 512
Writing fd = 9, addr = 24997888, buff = 89c01820, size = 512
Writing fd = 9, addr = 24998400, buff = 89c01820, size = 512
Writing fd = 9, addr = 24998912, buff = 89c01820, size = 512
Writing fd = 9, addr = 24999424, buff = 89c01820, size = 512
Writing fd = 9, addr = 24999936, buff = 89c01820, size = 512
Writing fd = 9, addr = 25000448, buff = 89c01820, size = 512
Writing fd = 9, addr = 25000960, buff = 89c01820, size = 512
Writing fd = 9, addr = 25001472, buff = 89c01820, size = 512
Writing fd = 9, addr = 25001984, buff = 89c01820, size = 512
Writing fd = 9, addr = 25002496, buff = 89c01820, size = 512
Writing fd = 9, addr = 25003008, buff = 89c01820, size = 512
Writing fd = 9, addr = 25003520, buff = 89c01820, size = 512
Writing fd = 9, addr = 25004032, buff = 79ffa800, size = 512
Writing fd = 9, addr = 25004544, buff = 79ffa750, size = 512
Writing fd = 9, addr = 512, buff = 8c405710, size = 861696 (full message with headers and body, space reused)

Full messages and ACK records are laid out sequentially and interwoven. ACK doesn't clean up message header. This design under heavy load may lead to excessive datastore usage and need for frequent compaction maintenance.

JMS headers with almost nothing set take 213 bytes. Minus 28 bytes for JMSMessageID it is 185 bytes on disk.

Executable Linux shared library

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

const char interp[] __attribute__((section(".interp"))) = "/lib64/ld-linux-x86-64.so.2";

void test() {
        printf("test\r\n");
}

extern "C" void _main(int argc, char **argv) {
        printf("main\r\n");
        test();
        exit(0);
}

user@user-Aspire-4530 ~/DEV $ g++ -shared -fPIC -o libtest.so libtest.c -Wl,-e,_main
user@user-Aspire-4530 ~/DEV $ LD_PRELOAD=./libtest.so ls
libtest.c  libtest.o  libtest.so
user@user-Aspire-4530 ~/DEV $ ./libtest.so 
main
test
user@user-Aspire-4530 ~/DEV $ readelf -l /bin/ls | grep interpreter

Maurice Moss

Hejterzy PO

Master Chef

Politechnika

Tibco BW Generic XPath Extractor