Merge pull request #4 from dbrumbaugh/master

Updates for VLDB revision

1 files changed, 56 insertions, 29 deletions

diff --git a/include/query/irs.h b/include/query/irs.h
index e2d9325..879d070 100644
--- a/include/query/irs.h
+++ b/include/query/irs.h
@@ -40,7 +40,12 @@ struct BufferState {
     size_t sample_size;
     BufferView<R> *buffer;
 
+    psudb::Alias *alias;
+
     BufferState(BufferView<R> *buffer) : buffer(buffer) {}
+    ~BufferState() {
+        delete alias;
+    }
 };
 
 template <RecordInterface R, ShardInterface<R> S, bool Rejection=true>
@@ -72,6 +77,7 @@ public:
 
         res->cutoff = res->buffer->get_record_count();
         res->sample_size = 0;
+        res->alias = nullptr;
 
         if constexpr (Rejection) {
             return res;
@@ -96,39 +102,51 @@ public:
         std::vector<size_t> shard_sample_sizes(shard_states.size()+1, 0);
         size_t buffer_sz = 0;
 
-        std::vector<size_t> weights;
-        if constexpr (Rejection) {
-            weights.push_back((bs) ? bs->cutoff : 0);
-        } else {
-            weights.push_back((bs) ? bs->records.size() : 0);
+        /* for simplicity of static structure testing */
+        if (!bs) {
+            assert(shard_states.size() == 1);
+            auto state = (State<R> *) shard_states[0];
+            state->sample_size = p->sample_size;
+            return;
         }
 
-        size_t total_weight = 0;
-        for (auto &s : shard_states) {
-            auto state = (State<R> *) s;
-            total_weight += state->total_weight;
-            weights.push_back(state->total_weight);
-        }
+        /* we only need to build the shard alias on the first call */
+        if (bs->alias == nullptr) {
+            std::vector<size_t> weights;
+            if constexpr (Rejection) {
+                weights.push_back((bs) ? bs->cutoff : 0);
+            } else {
+                weights.push_back((bs) ? bs->records.size() : 0);
+            }
 
-        // if no valid records fall within the query range, just
-        // set all of the sample sizes to 0 and bail out.
-        if (total_weight == 0) {
-            for (size_t i=0; i<shard_states.size(); i++) {
-                auto state = (State<R> *) shard_states[i];
-                state->sample_size = 0;
+            size_t total_weight = weights[0];
+            for (auto &s : shard_states) {
+                auto state = (State<R> *) s;
+                total_weight += state->total_weight;
+                weights.push_back(state->total_weight);
             }
 
-            return;
-        }
+            // if no valid records fall within the query range, just
+            // set all of the sample sizes to 0 and bail out.
+            if (total_weight == 0) {
+                for (size_t i=0; i<shard_states.size(); i++) {
+                    auto state = (State<R> *) shard_states[i];
+                    state->sample_size = 0;
+                }
 
-        std::vector<double> normalized_weights;
-        for (auto w : weights) {
-            normalized_weights.push_back((double) w / (double) total_weight);
+                return;
+            }
+
+            std::vector<double> normalized_weights;
+            for (auto w : weights) {
+                normalized_weights.push_back((double) w / (double) total_weight);
+            }
+            
+            bs->alias = new psudb::Alias(normalized_weights);
         }
 
-        auto shard_alias = psudb::Alias(normalized_weights);
         for (size_t i=0; i<p->sample_size; i++) {
-            auto idx = shard_alias.get(p->rng);            
+            auto idx = bs->alias->get(p->rng);            
             if (idx == 0) {
                 buffer_sz++;
             } else {
@@ -198,16 +216,12 @@ public:
         return result;
     }
 
-    static std::vector<R> merge(std::vector<std::vector<Wrapped<R>>> &results, void *parms) {
-        std::vector<R> output;
-
+    static void merge(std::vector<std::vector<Wrapped<R>>> &results, void *parms, std::vector<R> &output) {
         for (size_t i=0; i<results.size(); i++) {
             for (size_t j=0; j<results[i].size(); j++) {
                 output.emplace_back(results[i][j].rec);
             }
         }
-
-        return output;
     }
 
     static void delete_query_state(void *state) {
@@ -219,5 +233,18 @@ public:
         auto s = (BufferState<R> *) state;
         delete s;
     }
+
+    static bool repeat(void *parms, std::vector<R> &results, std::vector<void*> states, void* buffer_state) {
+        auto p = (Parms<R> *)  parms;
+
+        if (results.size() < p->sample_size) {
+            auto q = *p;
+            q.sample_size -= results.size();
+            process_query_states(&q, states, buffer_state);
+            return true;
+        }
+
+        return false;
+    }
 };
 }}