/** * When this class is loaded, preload the cache with a few items which we think will often be * needed. This can avoid the necessity of running a belief network context in simple problems. */ static { System.err.println("PiHelperLoader.static: preload the helper cache."); helper_cache = new Hashtable(); Vector seq = new Vector(); seq.addElement(riso.distributions.ConditionalDiscrete.class); seq.addElement(riso.distributions.Discrete.class); helper_cache.put( new HelperCacheKey("pi", seq), riso.distributions.computes_pi.ConditionalDiscrete_Discrete.class); seq = new Vector(); seq.addElement(riso.distributions.Discrete.class); helper_cache.put( new HelperCacheKey("lambda", seq), riso.distributions.computes_lambda.Discrete.class); seq = new Vector(); seq.addElement(riso.distributions.AbstractDistribution.class); seq.addElement(riso.distributions.AbstractDistribution.class); helper_cache.put( new HelperCacheKey("pi_message", seq), riso.distributions.computes_pi_message.AbstractDistribution_AbstractDistribution.class); seq = new Vector(); seq.addElement(riso.distributions.ConditionalDiscrete.class); seq.addElement(riso.distributions.Discrete.class); seq.addElement(riso.distributions.Discrete.class); helper_cache.put( new HelperCacheKey("lambda_message", seq), riso.distributions.computes_lambda_message.ConditionalDiscrete_Discrete_Discrete.class); seq = new Vector(); seq.addElement(riso.distributions.ConditionalDiscrete.class); seq.addElement(riso.distributions.Discrete.class); helper_cache.put( new HelperCacheKey("lambda_message", seq), riso.distributions.computes_lambda_message.ConditionalDiscrete_Discrete_.class); seq = new Vector(); seq.addElement(riso.distributions.Discrete.class); seq.addElement(riso.distributions.Discrete.class); helper_cache.put( new HelperCacheKey("posterior", seq), riso.distributions.computes_posterior.Discrete_Discrete.class); System.err.println("PiHelperLoader.static: helper_cache.size(): " + helper_cache.size()); }
/** * Check the helpers currently stored in the helper cache to see if any of them can handle the * sequence we've just been given. This avoids pinging the belief network context to get a helper * list. */ public static Class find_helper_class1( Vector seq, String helper_type, int[] max_class_score, int[] max_count_score) throws ClassNotFoundException { int[] class_score1 = new int[1], count_score1 = new int[1]; max_class_score[0] = -1; max_count_score[0] = -1; Class cmax_score = null; for (Enumeration e = helper_cache.keys(); e.hasMoreElements(); ) { try { HelperCacheKey key = (HelperCacheKey) e.nextElement(); if (!key.helper_type.equals(helper_type)) continue; Class c = (Class) helper_cache.get(key); SeqTriple[] sm = (SeqTriple[]) invoke_description(c); if (sm == null) continue; // apparently not a helper class if (MatchClassPattern.matches(sm, seq, class_score1, count_score1)) { if (class_score1[0] > max_class_score[0] || (class_score1[0] == max_class_score[0] && count_score1[0] > max_count_score[0])) { cmax_score = c; max_class_score[0] = class_score1[0]; max_count_score[0] = count_score1[0]; } } } catch (Exception e2) { } // eat it; stagger forward } if (Global.debug > 1) System.err.println( "PiHelperLoader.find_helper_class1: helper " + (cmax_score == null ? "is NOT" : "is") + " in cache."); if (cmax_score == null) // no luck; try to get a helper list from the bnc & plunge ahead return find_helper_class0(seq, helper_type, max_class_score, max_count_score); else // success! return cmax_score; }
/** * This method returns a <tt>Class</tt> for a helper which can handle the list of distributions * specified by <tt>seq1</tt>. We maintain a cache of recently-loaded helpers, so check the cache * before going to the trouble of searching for a helper. The cache is blown away every * <tt>HELPER_CACHE_REFRESH</tt> seconds. * * <p>If we can't find a helper in the cache, we must search through the list of available helpers * to find an appropriate one. First try to find helper using class sequence as specified by * <tt>seq</tt>. Whether or not that succeeds, promote any <tt>Gaussian</tt> in the sequence to * <tt>MixGaussians</tt>, and try again. If we get a better match on the second try, return the * helper thus found. */ public static Class find_helper_class(Vector seq1, String helper_type) throws ClassNotFoundException { // Let's see if an appropriate helper is in the cache. // If the cache is too old, empty it and search for the helper anew. if (System.currentTimeMillis() - cache_timestamp > HELPER_CACHE_REFRESH) { helper_cache = new Hashtable(); cache_timestamp = System.currentTimeMillis(); // Go on and search for appropriate helper. } else { HelperCacheKey key = new HelperCacheKey(helper_type, seq1); Class helper_class = (Class) helper_cache.get(key); if (helper_class != null) { if (Global.debug > -1) System.err.println( "PiHelperLoader.find_helper_class: found helper class: " + helper_class + "; no need to search."); return helper_class; } // else no luck; we have to search for helper. } // Well, we didn't find a helper in the cache, so let's go to work. if (Global.debug > -1) System.err.println( "PiHelperLoader.find_helper_class: DID NOT FIND HELPER CLASS; NOW SEARCH."); Class c1 = null, c2 = null; ClassNotFoundException cnfe1 = null, cnfe2 = null; int[] class_score1 = new int[1], count_score1 = new int[1]; int[] class_score2 = new int[1], count_score2 = new int[1]; try { c1 = find_helper_class1(seq1, helper_type, class_score1, count_score1); } catch (ClassNotFoundException e) { cnfe1 = e; } // hang on, we may need to re-throw later. Class gaussian_class = Class.forName("riso.distributions.Gaussian"); MixGaussians mog = new MixGaussians(1, 1); Vector seq2 = new Vector(seq1.size()); for (int i = 0; i < seq1.size(); i++) if (gaussian_class.isAssignableFrom((Class) seq1.elementAt(i))) seq2.addElement(mog.getClass()); else seq2.addElement(seq1.elementAt(i)); try { c2 = find_helper_class1(seq2, helper_type, class_score2, count_score2); } catch (ClassNotFoundException e) { cnfe2 = e; } if (cnfe1 == null && cnfe2 == null) { // Both matched; see which one fits better. // Break ties in favor of the helper for non-promoted messages. if (class_score1[0] >= class_score2[0] || (class_score1[0] == class_score2[0] && count_score1[0] >= count_score2[0])) { if (Global.debug > 1) System.err.println( "\taccept helper " + c1 + " for non-promoted classes instead of " + c2); if (Global.debug > 1) System.err.println( "\t\t" + class_score1[0] + ", " + class_score2[0] + "; " + count_score1[0] + ", " + count_score2[0]); helper_cache.put(new HelperCacheKey(helper_type, seq1), c1); return c1; } else { if (Global.debug > 1) System.err.println("\taccept helper " + c2 + " for promoted classes instead of " + c1); if (Global.debug > 1) System.err.println( "\t\t" + class_score1[0] + ", " + class_score2[0] + "; " + count_score1[0] + ", " + count_score2[0]); helper_cache.put(new HelperCacheKey(helper_type, seq1), c2); return c2; } } else if (cnfe1 == null && cnfe2 != null) { // Only the first try matched, return it. helper_cache.put(new HelperCacheKey(helper_type, seq1), c1); return c1; } else if (cnfe1 != null && cnfe2 == null) { // Only the second try matched, return it. helper_cache.put(new HelperCacheKey(helper_type, seq1), c2); return c2; } else { // Neither try matched. Re-throw the exception generated by the first try. throw cnfe1; } }