/*
** 2016-12-28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file implements "key-value" performance test for SQLite.  The
** purpose is to compare the speed of SQLite for accessing large BLOBs
** versus reading those same BLOB values out of individual files in the
** filesystem.
**
** Run "kvtest --help" for further information, or see comments below.
*/
static const char zHelp[] = 
"Usage: kvhelp COMMAND ARGS...\n"
"\n"
"   kvhelp init DBFILE --count N --size M --pagesize X\n"
"\n"
"        Generate a new test database file named DBFILE containing N\n"
"        BLOBs each of size M bytes.  The page size of the new database\n"
"        file will be X\n"
"\n"
"   kvhelp export DBFILE DIRECTORY\n"
"\n"
"        Export all the blobs in the kv table of DBFILE into separate\n"
"        files in DIRECTORY.\n"
"\n"
"   kvhelp run DBFILE [options]\n"
"\n"
"        Run a performance test.  DBFILE can be either the name of a\n"
"        database or a directory containing sample files.  Options:\n"
"\n"
"             --count N            Read N blobs\n"
"             --blob-api           Use the BLOB API\n"
"             --random             Read blobs in a random order\n"
"             --desc               Read blobs in descending order\n"
"             --max-id N           Maximum blob key to use\n"
"             --start N            Start reading with this blob key\n"
;

/* Reference resources used */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <assert.h>
#include <string.h>
#include "sqlite3.h"

/*
** Show thqe help text and quit.
*/
static void showHelp(void){
  fprintf(stdout, "%s", zHelp);
  exit(1);
}

/*
** Show an error message an quit.
*/
static void fatalError(const char *zFormat, ...){
  va_list ap;
  fprintf(stdout, "ERROR: ");
  va_start(ap, zFormat);
  vfprintf(stdout, zFormat, ap);
  va_end(ap);
  fprintf(stdout, "\n");
  exit(1);
}

/*
** Check the filesystem object zPath.  Determine what it is:
**
**    PATH_DIR     A directory
**    PATH_DB      An SQLite database
**    PATH_NEXIST  Does not exist
**    PATH_OTHER   Something else
*/
#define PATH_DIR     1
#define PATH_DB      2
#define PATH_NEXIST  0
#define PATH_OTHER   99
static int pathType(const char *zPath){
  struct stat x;
  int rc;
  if( access(zPath,R_OK) ) return PATH_NEXIST;
  memset(&x, 0, sizeof(x));
  rc = stat(zPath, &x);
  if( rc<0 ) return PATH_OTHER;
  if( S_ISDIR(x.st_mode) ) return PATH_DIR;
  if( (x.st_size%512)==0 ) return PATH_DB;
  return PATH_OTHER;
}

/*
** A Pseudo-random number generator with a fixed seed.  Use this so
** that the same sequence of "random" numbers are generated on each
** run, for repeatability.
*/
static unsigned int randInt(void){
  static unsigned int x = 0x333a13cd;
  static unsigned int y = 0xecb2adea;
  x = (x>>1) ^ ((1+~(x&1)) & 0xd0000001);
  y = y*1103515245 + 12345;
  return x^y;
}

/*
** Do database initialization.
*/
static int initMain(int argc, char **argv){
  char *zDb;
  int i, rc;
  int nCount = 1000;
  int sz = 10000;
  int pgsz = 4096;
  sqlite3 *db;
  char *zSql;
  char *zErrMsg = 0;

  assert( strcmp(argv[1],"init")==0 );
  assert( argc>=3 );
  zDb = argv[2];
  for(i=3; i<argc; i++){
    char *z = argv[i];
    if( z[0]!='-' ) fatalError("unknown argument: \"%s\"", z);
    if( z[1]=='-' ) z++;
    if( strcmp(z, "-count")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      nCount = atoi(argv[++i]);
      if( nCount<1 ) fatalError("the --count must be positive");
      continue;
    }
    if( strcmp(z, "-size")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      sz = atoi(argv[++i]);
      if( sz<1 ) fatalError("the --size must be positive");
      continue;
    }
    if( strcmp(z, "-pagesize")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      pgsz = atoi(argv[++i]);
      if( pgsz<512 || pgsz>65536 || ((pgsz-1)&pgsz)!=0 ){
        fatalError("the --pagesize must be power of 2 between 512 and 65536");
      }
      continue;
    }
    fatalError("unknown option: \"%s\"", argv[i]);
  }
  rc = sqlite3_open(zDb, &db);
  if( rc ){
    fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
  }
  zSql = sqlite3_mprintf(
    "DROP TABLE IF EXISTS kv;\n"
    "PRAGMA page_size=%d;\n"
    "VACUUM;\n"
    "BEGIN;\n"
    "CREATE TABLE kv(k INTEGER PRIMARY KEY, v BLOB);\n"
    "WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<%d)"
    " INSERT INTO kv(k,v) SELECT x, randomblob(%d) FROM c;\n"
    "COMMIT;\n",
    pgsz, nCount, sz
  );
  rc = sqlite3_exec(db, zSql, 0, 0, &zErrMsg);
  if( rc ) fatalError("database create failed: %s", zErrMsg);
  sqlite3_free(zSql);
  sqlite3_close(db);
  return 0;
}

/*
** Implementation of the "writefile(X,Y)" SQL function.  The argument Y
** is written into file X.  The number of bytes written is returned.  Or
** NULL is returned if something goes wrong, such as being unable to open
** file X for writing.
*/
static void writefileFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  FILE *out;
  const char *z;
  sqlite3_int64 rc;
  const char *zFile;

  zFile = (const char*)sqlite3_value_text(argv[0]);
  if( zFile==0 ) return;
  out = fopen(zFile, "wb");
  if( out==0 ) return;
  z = (const char*)sqlite3_value_blob(argv[1]);
  if( z==0 ){
    rc = 0;
  }else{
    rc = fwrite(z, 1, sqlite3_value_bytes(argv[1]), out);
  }
  fclose(out);
  sqlite3_result_int64(context, rc);
}

/*
** Export the kv table to individual files in the filesystem
*/
static int exportMain(int argc, char **argv){
  char *zDb;
  char *zDir;
  sqlite3 *db;
  char *zSql;
  int rc;
  char *zErrMsg = 0;

  assert( strcmp(argv[1],"export")==0 );
  assert( argc>=3 );
  zDb = argv[2];
  if( argc!=4 ) fatalError("Usage: kvtest export DATABASE DIRECTORY");
  zDir = argv[3];
  if( pathType(zDir)!=PATH_DIR ){
    fatalError("object \"%s\" is not a directory", zDir);
  }
  rc = sqlite3_open(zDb, &db);
  if( rc ){
    fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
  }
  sqlite3_create_function(db, "writefile", 2, SQLITE_UTF8, 0,
                          writefileFunc, 0, 0);
  zSql = sqlite3_mprintf(
    "SELECT writefile(printf('%s/%%06d',k),v) FROM kv;",
    zDir
  );
  rc = sqlite3_exec(db, zSql, 0, 0, &zErrMsg);
  if( rc ) fatalError("database create failed: %s", zErrMsg);
  sqlite3_free(zSql);
  sqlite3_close(db);
  return 0;
}

/*
** Read the content of file zName into memory obtained from sqlite3_malloc64()
** and return a pointer to the buffer. The caller is responsible for freeing 
** the memory. 
**
** If parameter pnByte is not NULL, (*pnByte) is set to the number of bytes
** read.
**
** For convenience, a nul-terminator byte is always appended to the data read
** from the file before the buffer is returned. This byte is not included in
** the final value of (*pnByte), if applicable.
**
** NULL is returned if any error is encountered. The final value of *pnByte
** is undefined in this case.
*/
static unsigned char *readFile(const char *zName, int *pnByte){
  FILE *in = fopen(zName, "rb");
  long nIn;
  size_t nRead;
  unsigned char *pBuf;
  if( in==0 ) return 0;
  fseek(in, 0, SEEK_END);
  nIn = ftell(in);
  rewind(in);
  pBuf = sqlite3_malloc64( nIn+1 );
  if( pBuf==0 ) return 0;
  nRead = fread(pBuf, nIn, 1, in);
  fclose(in);
  if( nRead!=1 ){
    sqlite3_free(pBuf);
    return 0;
  }
  pBuf[nIn] = 0;
  if( pnByte ) *pnByte = nIn;
  return pBuf;
}

/*
** Return the current time in milliseconds since the beginning of
** the Julian epoch.
*/
static sqlite3_int64 timeOfDay(void){
  static sqlite3_vfs *clockVfs = 0;
  sqlite3_int64 t;
  if( clockVfs==0 ) clockVfs = sqlite3_vfs_find(0);
  if( clockVfs->iVersion>=2 && clockVfs->xCurrentTimeInt64!=0 ){
    clockVfs->xCurrentTimeInt64(clockVfs, &t);
  }else{
    double r;
    clockVfs->xCurrentTime(clockVfs, &r);
    t = (sqlite3_int64)(r*86400000.0);
  }
  return t;
}

/* Blob access order */
#define ORDER_ASC     1
#define ORDER_DESC    2
#define ORDER_RANDOM  3

/*
** Run a performance test
*/
static int runMain(int argc, char **argv){
  int eType;                  /* Is zDb a database or a directory? */
  char *zDb;                  /* Database or directory name */
  int i;                      /* Loop counter */
  int rc;                     /* Return code from SQLite calls */
  int nCount = 1000;          /* Number of blob fetch operations */
  int nExtra = 0;             /* Extra cycles */
  int iKey = 1;               /* Next blob key */
  int iMax = 1000;            /* Largest allowed key */
  int bBlobApi = 0;           /* Use the incremental blob I/O API */
  int eOrder = ORDER_ASC;     /* Access order */
  sqlite3 *db = 0;            /* Database connection */
  sqlite3_stmt *pStmt = 0;    /* Prepared statement for SQL access */
  sqlite3_blob *pBlob = 0;    /* Handle for incremental Blob I/O */
  sqlite3_int64 tmStart;      /* Start time */
  sqlite3_int64 tmElapsed;    /* Elapsed time */
  int nData = 0;              /* Bytes of data */
  sqlite3_int64 nTotal = 0;   /* Total data read */
  unsigned char *pData;       /* Content of the blob */
  

  assert( strcmp(argv[1],"run")==0 );
  assert( argc>=3 );
  zDb = argv[2];
  eType = pathType(zDb);
  if( eType==PATH_OTHER ) fatalError("unknown object type: \"%s\"", zDb);
  if( eType==PATH_NEXIST ) fatalError("object does not exist: \"%s\"", zDb);
  for(i=3; i<argc; i++){
    char *z = argv[i];
    if( z[0]!='-' ) fatalError("unknown argument: \"%s\"", z);
    if( z[1]=='-' ) z++;
    if( strcmp(z, "-count")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      nCount = atoi(argv[++i]);
      if( nCount<1 ) fatalError("the --count must be positive");
      continue;
    }
    if( strcmp(z, "-max-id")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      iMax = atoi(argv[++i]);
      if( iMax<1 ) fatalError("the --max-id must be positive");
      continue;
    }
    if( strcmp(z, "-start")==0 ){
      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
      iKey = atoi(argv[++i]);
      if( iKey<1 ) fatalError("the --start must be positive");
      continue;
    }
    if( strcmp(z, "-random")==0 ){
      eOrder = ORDER_RANDOM;
      continue;
    }
    if( strcmp(z, "-asc")==0 ){
      eOrder = ORDER_ASC;
      continue;
    }
    if( strcmp(z, "-desc")==0 ){
      eOrder = ORDER_DESC;
      continue;
    }
    if( strcmp(z, "-blob-api")==0 ){
      bBlobApi = 1;
      continue;
    }
    fatalError("unknown option: \"%s\"", argv[i]);
  }
  tmStart = timeOfDay();
  if( eType==PATH_DB ){
    rc = sqlite3_open(zDb, &db);
    if( rc ){
      fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
    }
    sqlite3_exec(db, "BEGIN", 0, 0, 0);
  }
  for(i=0; i<nCount; i++){
    if( eType==PATH_DIR ){
      /* CASE 1: Reading blobs out of separate files */
      char *zKey;
      zKey = sqlite3_mprintf("%s/%06d", zDb, iKey);
      nData = 0;
      pData = readFile(zKey, &nData);
      sqlite3_free(zKey);
      sqlite3_free(pData);
    }else if( bBlobApi ){
      /* CASE 2: Reading from database using the incremental BLOB I/O API */
      if( pBlob==0 ){
        rc = sqlite3_blob_open(db, "main", "kv", "v", iKey, 0, &pBlob);
        if( rc ){
          fatalError("could not open sqlite3_blob handle: %s",
                     sqlite3_errmsg(db));
        }
      }else{
        rc = sqlite3_blob_reopen(pBlob, iKey);
      }
      if( rc==SQLITE_OK ){
        nData = sqlite3_blob_bytes(pBlob);
        pData = sqlite3_malloc( nData+1 );
        if( pData==0 ) fatalError("cannot allocate %d bytes", nData+1);
        rc = sqlite3_blob_read(pBlob, pData, nData, 0);
        if( rc!=SQLITE_OK ){
          fatalError("could not read the blob at %d: %s", iKey,
                     sqlite3_errmsg(db));
        }
        sqlite3_free(pData);
      }
    }else{
      /* CASE 3: Reading from database using SQL */
      if( pStmt==0 ){
        rc = sqlite3_prepare_v2(db, 
               "SELECT v FROM kv WHERE k=?1", -1, &pStmt, 0);
        if( rc ){
          fatalError("cannot prepare query: %s", sqlite3_errmsg(db));
        }
      }else{
        sqlite3_reset(pStmt);
      }
      sqlite3_bind_int(pStmt, 1, iKey);
      rc = sqlite3_step(pStmt);
      if( rc==SQLITE_ROW ){
        nData = sqlite3_column_bytes(pStmt, 0);
        pData = (unsigned char*)sqlite3_column_blob(pStmt, 0);
      }else{
        nData = 0;
      }
    }
    if( eOrder==ORDER_ASC ){
      iKey++;
      if( iKey>iMax ) iKey = 1;
    }else if( eOrder==ORDER_DESC ){
      iKey--;
      if( iKey<=0 ) iKey = iMax;
    }else{
      iKey = (randInt()%iMax)+1;
    }
    nTotal += nData;
    if( nData==0 ){ nCount++; nExtra++; }
  }
  if( pStmt ) sqlite3_finalize(pStmt);
  if( pBlob ) sqlite3_blob_close(pBlob);
  if( db ) sqlite3_close(db);
  tmElapsed = timeOfDay() - tmStart;
  if( nExtra ){
    printf("%d cycles due to %d misses\n", nCount, nExtra);
  }
  printf("Total elapsed time: %.3f\n", tmElapsed/1000.0);
  printf("Microseconds per BLOB read: %.3f\n", tmElapsed*1000.0/nCount);
  printf("Content read rate: %.1f MB/s\n", nTotal/(1000.0*tmElapsed));
  return 0;
}


int main(int argc, char **argv){
  if( argc<3 ) showHelp();
  if( strcmp(argv[1],"init")==0 ){
    return initMain(argc, argv);
  }
  if( strcmp(argv[1],"export")==0 ){
    return exportMain(argc, argv);
  }
  if( strcmp(argv[1],"run")==0 ){
    return runMain(argc, argv);
  }
  showHelp();
  return 0;
}