changeset 284:cacad987d785

Really finish with the sampling branch, this time merging all of it,
yes, even the last revision.  (The last revision was one that seeded the
RNG with the current time, which is helpful when trying to get multiple
independent-ish samples from the same database...)

--- a/audioDB.cpp	Thu Jul 03 08:50:57 2008 +0000
+++ b/audioDB.cpp	Mon Jul 07 08:57:06 2008 +0000
@@ -97,6 +97,9 @@
   if(l2normTable)
     munmap(l2normTable, l2normTableLength);
 
+  if(rng)
+    gsl_rng_free(rng);
+
   if(dbfid>0)
     close(dbfid);
   if(infid>0)

--- a/audioDB.h	Thu Jul 03 08:50:57 2008 +0000
+++ b/audioDB.h	Mon Jul 07 08:57:06 2008 +0000
@@ -159,6 +159,8 @@
   char* indata;
   struct stat statbuf;  
   dbTableHeaderPtr dbH;
+
+  gsl_rng *rng;
   
   char *fileTable;
   unsigned* trackTable;
@@ -224,6 +226,7 @@
   void set_up_db(double **snp, double **vsnp, double **spp, double **vspp, double **mddp, unsigned int *dvp);
   void query_loop(const char* dbName, const char* inFile, Reporter *reporter);
 
+  void initRNG();
   void initDBHeader(const char *dbName);
   void initInputFile(const char *inFile);
   void initTables(const char* dbName, const char* inFile);
@@ -251,7 +254,7 @@
   void batchinsert(const char* dbName, const char* inFile);
   void query(const char* dbName, const char* inFile, adb__queryResponse *adbQueryResponse=0);
   void status(const char* dbName, adb__statusResponse *adbStatusResponse=0);
-  unsigned random_track(unsigned *propTable, unsigned total, gsl_rng *);
+  unsigned random_track(unsigned *propTable, unsigned total);
   void sample(const char *dbName);
   void ws_status(const char*dbName, char* hostport);
   void ws_query(const char*dbName, const char *trackKey, const char* hostport);
@@ -285,6 +288,7 @@
   db(0), \
   indata(0), \
   dbH(0), \
+  rng(0), \
   fileTable(0), \
   trackTable(0), \
   dataBuf(0), \

--- a/common.cpp	Thu Jul 03 08:50:57 2008 +0000
+++ b/common.cpp	Mon Jul 07 08:57:06 2008 +0000
@@ -70,6 +70,15 @@
   }
 }
 
+void audioDB::initRNG() {
+  rng = gsl_rng_alloc(gsl_rng_mt19937);
+  if(!rng) {
+    error("could not allocate Random Number Generator");
+  }
+  /* FIXME: maybe we should use a real source of entropy? */
+  gsl_rng_set(rng, time(NULL));
+}
+
 void audioDB::initDBHeader(const char* dbName) {
   if ((dbfid = open(dbName, forWrite ? O_RDWR : O_RDONLY)) < 0) {
     error("Can't open database file", dbName, "open");
@@ -179,6 +188,13 @@
 }
 
 void audioDB::initTables(const char* dbName, const char* inFile = 0) {
+  /* FIXME: initRNG() really logically belongs in the audioDB
+     contructor.  However, there are of the order of four constructors
+     at the moment, and more to come from API implementation.  Given
+     that duplication, I think this is the least worst place to put
+     it; the assumption is that nothing which doesn't look at a
+     database will need an RNG.  -- CSR, 2008-07-02 */
+  initRNG();
   initDBHeader(dbName);
   initInputFile(inFile);
 }

--- a/sample.cpp	Thu Jul 03 08:50:57 2008 +0000
+++ b/sample.cpp	Mon Jul 07 08:57:06 2008 +0000
@@ -36,7 +36,7 @@
   return c;
 }
 
-unsigned audioDB::random_track(unsigned *propTable, unsigned total, gsl_rng *rng) {
+unsigned audioDB::random_track(unsigned *propTable, unsigned total) {
   /* FIXME: make this O(1) by using the alias-rejection method, or
      some other sensible method of sampling from a discrete
      distribution. */
@@ -57,18 +57,6 @@
 void audioDB::sample(const char *dbName) {
   initTables(dbName, 0);
 
-  gsl_rng *rng = gsl_rng_alloc(gsl_rng_mt19937);
-
-  /* FIXME: in Real Life we'll want to initialize the RNG using
-     /dev/random or the current time or something, like this:
-
-     unsigned int seed;
-     int fd = open("/dev/urandom", O_RDONLY);
-     read(fd, &seed, 4);
-     
-     gsl_rng_set(rng, seed);
-  */
-
   // build track offset table (FIXME: cut'n'pasted from query.cpp)
   off_t *trackOffsetTable = new off_t[dbH->numFiles];
   unsigned cumTrack=0;
@@ -105,8 +93,8 @@
   double sumlogdist = 0;
 
   for (unsigned int i = 0; i < nsamples;) {
-    unsigned track1 = random_track(propTable, total, rng);
-    unsigned track2 = random_track(propTable, total, rng);
+    unsigned track1 = random_track(propTable, total);
+    unsigned track2 = random_track(propTable, total);
 
     if(track1 == track2)
       continue;