Initial port of DynamicExtension framework

1 files changed, 633 insertions, 0 deletions

diff --git a/include/framework/DynamicExtension.h b/include/framework/DynamicExtension.h
new file mode 100644
index 0000000..93de24f
--- /dev/null
+++ b/include/framework/DynamicExtension.h
@@ -0,0 +1,633 @@
+#pragma once
+
+#include <atomic>
+#include <numeric>
+#include <cstdio>
+#include<vector>
+
+#include "framework/MutableBuffer.h"
+#include "framework/InternalLevel.h"
+#include "ds/Alias.h"
+#include "util/timer.h"
+
+namespace de {
+
+thread_local size_t sampling_attempts = 0;
+thread_local size_t sampling_rejections = 0;
+thread_local size_t deletion_rejections = 0;
+thread_local size_t bounds_rejections = 0;
+thread_local size_t tombstone_rejections = 0;
+thread_local size_t buffer_rejections = 0;
+
+/*
+ * thread_local size_t various_sampling_times go here.
+ */
+thread_local size_t sample_range_time = 0;
+thread_local size_t alias_time = 0;
+thread_local size_t alias_query_time = 0;
+thread_local size_t rejection_check_time = 0;
+thread_local size_t buffer_sample_time = 0;
+thread_local size_t memlevel_sample_time = 0;
+thread_local size_t disklevel_sample_time = 0;
+thread_local size_t sampling_bailouts = 0;
+
+
+/*
+ * LSM Tree configuration global variables
+ */
+
+// True for buffer rejection sampling
+static constexpr bool LSM_REJ_SAMPLE = false;
+
+// True for leveling, false for tiering
+static constexpr bool LSM_LEVELING = false;
+
+static constexpr bool DELETE_TAGGING = true;
+
+// TODO: Replace the constexpr bools above
+// with template parameters based on these
+// enums.
+enum class LayoutPolicy {
+    LEVELING,
+    TEIRING
+};
+
+enum class DeletePolicy {
+    TOMBSTONE,
+    TAGGING
+};
+
+typedef ssize_t level_index;
+
+template <typename K, typename V, typename W=void>
+class DynamicExtension {
+    typedef WIRS<K,V,W> Shard;
+    typedef MutableBuffer<K,V,W> MBuffer;
+    typedef Record<K, V, W> Rec;
+
+public:
+    DynamicExtension(size_t buffer_cap, size_t buffer_delete_cap, size_t scale_factor,
+                     double max_delete_prop, double max_rejection_prop, gsl_rng *rng) 
+        : m_active_buffer(0), 
+          m_scale_factor(scale_factor), 
+          m_max_delete_prop(max_delete_prop),
+          m_max_rejection_rate(max_rejection_prop),
+          m_last_level_idx(-1),
+          m_buffer_1(new MutableBuffer<K,V,W>(buffer_cap, LSM_REJ_SAMPLE, buffer_delete_cap, rng)), 
+          m_buffer_2(new MutableBuffer<K,V,W>(buffer_cap, LSM_REJ_SAMPLE, buffer_delete_cap, rng)),
+          m_buffer_1_merging(false), m_buffer_2_merging(false) {}
+
+    ~DynamicExtension() {
+        delete m_buffer_1;
+        delete m_buffer_2;
+
+        for (size_t i=0; i<m_levels.size(); i++) {
+            delete m_levels[i];
+        }
+    }
+
+    int delete_record(const K& key, const V& val, gsl_rng *rng) {
+        assert(DELETE_TAGGING);
+
+        auto buffer = get_buffer();
+        // Check the levels first. This assumes there aren't 
+        // any undeleted duplicate records.
+        for (auto level : m_levels) {
+            if (level && level->delete_record(key, val)) {
+                return 1;
+            }
+        }
+
+        // the buffer will take the longest amount of time, and 
+        // probably has the lowest probability of having the record,
+        // so we'll check it last.
+        return buffer->delete_record(key, val);
+    }
+
+    int append(const K& key, const V& val, W weight, bool tombstone, gsl_rng *rng) {
+        // NOTE: single-threaded implementation only
+        MutableBuffer<K,V,W> *buffer;
+        while (!(buffer = buffer()))
+            ;
+        
+        if (buffer->is_full()) {
+            merge_buffer(rng);
+        }
+
+        return buffer->append(key, val, weight, tombstone);
+    }
+
+    void range_sample(Record<K,V,W> *sample_set, const K& lower_key, const K& upper_key, size_t sample_sz, gsl_rng *rng) {
+        auto buffer = get_buffer();
+        Alias *buffer_alias = nullptr;
+        std::vector<Record<K,V,W> *> buffer_records;
+        size_t buffer_cutoff = 0;
+
+        W buffer_weight;
+        if (LSM_REJ_SAMPLE) {
+            buffer_weight = buffer->get_total_weight(); 
+            buffer_cutoff = buffer->get_record_count() - 1;
+        } else {
+            buffer_weight = buffer->get_sample_range(lower_key, upper_key, buffer_records, &buffer_alias, &buffer_cutoff);
+        }
+
+        // Get the shard weights for each level. Index 0 is the buffer,
+        // represented by nullptr.
+        std::vector<std::pair<ShardID, Shard*>> shards;
+        std::vector<void*> states;
+        shards.push_back({{-1, -1}, nullptr});
+        states.push_back(nullptr);
+
+        std::vector<double> shard_weights;
+        shard_weights.push_back(buffer_weight);
+
+        for (auto &level : m_levels) {
+            level->get_shard_weights(shard_weights, shards, states, lower_key, upper_key);
+        }
+
+        if (shard_weights.size() == 1 && shard_weights[0] == 0) {
+            if (buffer_alias) delete buffer_alias;
+            for (auto& x: states) Shard::delete_state(x);
+            sampling_bailouts++;
+            return; // no records in the sampling range
+        }
+
+        double tot_weight = std::accumulate(shard_weights.begin(), shard_weights.end(), 0);
+        for (auto& w: shard_weights) w /= tot_weight;
+
+        // Construct alias structure
+        auto alias = Alias(shard_weights);
+
+        std::vector<size_t> shard_samples(shard_weights.size(), 0);
+
+        size_t rejections = sample_sz;
+        size_t sample_idx = 0;
+
+        size_t buffer_rejections = 0;
+        
+        do {
+            for (size_t i=0; i<rejections; i++) {
+                shard_samples[alias.get(rng)] += 1;
+            }
+
+            rejections = 0;
+
+            while (shard_samples[0] > 0) {
+                const Record<K,V,W> *rec;
+                if (LSM_REJ_SAMPLE) {
+                    rec = buffer->get_sample(lower_key, upper_key, rng);
+                } else {
+                    rec = buffer_records[buffer_alias->get(rng)];
+                }
+
+                if (DELETE_TAGGING) {
+                    if (rec && !rec->get_delete_status()) {
+                        sample_set[sample_idx++] = *rec;
+                    } else {
+                        rejections++;
+                    }
+                } else {
+                    if (rec && !buffer->check_tombstone(rec->key, rec->value)) {
+                        sample_set[sample_idx++] = *rec;
+                    } else {
+                        rejections++;
+                    }
+                }
+
+                shard_samples[0]--;
+
+                // Assume nothing in buffer and bail out.
+                // FIXME: rather than a bailout, we could switch to non-rejection 
+                // sampling, but that would require rebuilding the full alias structure. 
+                // Wouldn't be too hard to do, but for the moment I'll just do this.
+                if (LSM_REJ_SAMPLE && buffer_rejections >= sample_sz && sample_idx == 0 && shard_weights.size() == 1) {
+                    if (buffer_alias) delete buffer_alias;
+                    //for (auto& x: states) delete x;
+                    sampling_bailouts++;
+                    return; // no records in the sampling range
+                }
+            }
+
+            std::vector<Rec> results;
+            for (size_t i=1; i<shard_samples.size(); i++) {
+                results.reserve(shard_samples[i]);
+
+                shards[i].second->get_samples(states[i], results, lower_key, upper_key, shard_samples[i], rng);
+
+                for (size_t i=0; i<results.size(); i++) {
+                    if (results[i]->is_tombstone() || is_deleted(results[i], shards[i].first, buffer, buffer_cutoff)) {
+                        rejections++;
+                        continue;
+                    }
+
+                    sample_set[sample_idx++] = results[i]; 
+                }
+
+                shard_samples[i] = 0;
+                results.clear();
+            }
+
+        } while (sample_idx < sample_sz);
+
+        if (buffer_alias) delete buffer_alias;
+        for (auto& x: states) Shard::delete_state(x);
+
+        enforce_rejection_rate_maximum(rng);
+    }
+
+    // Checks the tree and buffer for a tombstone corresponding to
+    // the provided record in any shard *above* the shid, which
+    // should correspond to the shard containing the record in question
+    // 
+    // Passing INVALID_SHID indicates that the record exists within the buffer
+    bool is_deleted(const Record<K,V,W> *record, const ShardID &shid, MutableBuffer<K,V,W> *buffer, size_t buffer_cutoff) {
+        // If tagging is enabled, we just need to check if the record has the delete tag set
+        if (DELETE_TAGGING) {
+            return record->get_delete_status();
+        }
+
+        // Otherwise, we need to look for a tombstone.
+
+        // check for tombstone in the buffer. This will require accounting for the cutoff eventually.
+        if (buffer->check_tombstone(record->key, record->value)) {
+            return true;
+        }
+
+        // if the record is in the buffer, then we're done.
+        if (shid == INVALID_SHID) {
+            return false;
+        }
+
+        for (size_t lvl=0; lvl<=shid.level_idx; lvl++) {
+            if (m_levels[lvl]->check_tombstone(0, record->key, record->value)) {
+                return true;
+            }
+        }
+
+        // check the level containing the shard
+        return m_levels[shid.level_idx]->check_tombstone(shid.shard_idx + 1, record->key, record->value);
+    }
+
+
+    size_t get_record_cnt() {
+        size_t cnt = get_buffer()->get_record_count();
+
+        for (size_t i=0; i<m_levels.size(); i++) {
+            if (m_levels[i]) cnt += m_levels[i]->get_record_cnt();
+        }
+
+        return cnt;
+    }
+
+
+    size_t get_tombstone_cnt() {
+        size_t cnt = get_buffer()->get_tombstone_count();
+
+        for (size_t i=0; i<m_levels.size(); i++) {
+            if (m_levels[i]) cnt += m_levels[i]->get_tombstone_count();
+        }
+
+        return cnt;
+    }
+
+    size_t get_height() {
+        return m_levels.size();
+    }
+
+    size_t get_memory_utilization() {
+        size_t cnt = m_buffer_1->get_memory_utilization() + m_buffer_2->get_memory_utilization();
+
+        for (size_t i=0; i<m_levels.size(); i++) {
+            if (m_levels[i]) cnt += m_levels[i]->get_memory_utilization();
+        }
+
+        return cnt;
+    }
+
+    size_t get_aux_memory_utilization() {
+        size_t cnt = m_buffer_1->get_aux_memory_utilization() + m_buffer_2->get_aux_memory_utilization();
+
+        for (size_t i=0; i<m_levels.size(); i++) {
+            if (m_levels[i]) {
+                cnt += m_levels[i]->get_aux_memory_utilization();
+            }
+        }
+
+        return cnt;
+    }
+
+    bool validate_tombstone_proportion() {
+        long double ts_prop;
+        for (size_t i=0; i<m_levels.size(); i++) {
+            if (m_levels[i]) {
+                ts_prop = (long double) m_levels[i]->get_tombstone_count() / (long double) calc_level_record_capacity(i);
+                if (ts_prop > (long double) m_max_delete_prop) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    size_t get_buffer_capacity() {
+        return m_buffer_1->get_capacity();
+    }
+    
+
+    Shard *create_ssi() {
+        std::vector<Shard *> shards;
+
+        if (m_levels.size() > 0) {
+            for (int i=m_levels.size() - 1; i>= 0; i--) {
+                if (m_levels[i]) {
+                    shards.emplace_back(m_levels[i]->get_merged_shard());
+                }
+            }
+        }
+
+        shards.emplace_back(new Shard(get_buffer(), nullptr, DELETE_TAGGING));
+
+        Shard *shards_array[shards.size()];
+
+        size_t j = 0;
+        for (size_t i=0; i<shards.size(); i++) {
+            if (shards[i]) {
+                shards_array[j++] = shards[i];
+            }
+        }
+
+        Shard *flattened = new Shard(shards_array, j, nullptr, DELETE_TAGGING);
+
+        for (auto shard : shards) {
+            delete shard;
+        }
+
+        return flattened;
+    }
+
+private:
+    MutableBuffer<K,V,W> *m_buffer_1;
+    MutableBuffer<K,V,W> *m_buffer_2;
+    std::atomic<bool> m_active_buffer;
+    std::atomic<bool> m_buffer_1_merging;
+    std::atomic<bool> m_buffer_2_merging;
+
+    size_t m_scale_factor;
+    double m_max_delete_prop;
+    double m_max_rejection_rate;
+
+    std::vector<InternalLevel<K,V,W> *> m_levels;
+
+    level_index m_last_level_idx;
+
+    MutableBuffer<K,V,W> *get_buffer() {
+        if (m_buffer_1_merging && m_buffer_2_merging) {
+            return nullptr;
+        }
+
+        return (m_active_buffer) ? m_buffer_2 : m_buffer_1;
+    }
+
+    inline bool rejection(const Record<K,V,W> *record, ShardID shid, const K& lower_bound, const K& upper_bound, MutableBuffer<K,V,W> *buffer, size_t buffer_cutoff) {
+        if (record->is_tombstone()) {
+            tombstone_rejections++;
+            return true;
+        } else if (record->key < lower_bound || record->key > upper_bound) {
+            bounds_rejections++;
+            return true;
+        } else if (is_deleted(record, shid, buffer, buffer, buffer_cutoff)) {
+            deletion_rejections++;
+            return true;
+        }
+
+        return false;
+    }
+
+    inline bool add_to_sample(const Record<K,V,W> *record, ShardID shid, const K& upper_key, const K& lower_key, char *io_buffer,
+                              Record<K,V,W> *sample_buffer, size_t &sample_idx, MutableBuffer<K,V,W> *buffer, size_t buffer_cutoff) {
+        TIMER_INIT();
+        TIMER_START();
+        sampling_attempts++;
+        if (!record || rejection(record, shid, lower_key, upper_key, io_buffer, buffer, buffer_cutoff)) {
+            sampling_rejections++;
+            return false;
+        }
+        TIMER_STOP();
+        rejection_check_time += TIMER_RESULT();
+
+        sample_buffer[sample_idx++] = *record;
+        return true;
+    }
+
+    /*
+     * Add a new level to the LSM Tree and return that level's index. Will
+     * automatically determine whether the level should be on memory or on disk,
+     * and act appropriately.
+     */
+    inline level_index grow() {
+        level_index new_idx;
+
+        size_t new_shard_cnt = (LSM_LEVELING) ? 1 : m_scale_factor;
+        new_idx = m_levels.size();
+        if (new_idx > 0) {
+            auto res = m_levels[new_idx - 1]->get_shard(0)->get_tombstone_count();
+            assert(res == 0);
+        }
+        m_levels.emplace_back(new InternalLevel<K,V,W>(new_idx, new_shard_cnt, DELETE_TAGGING));
+
+        m_last_level_idx++;
+        return new_idx;
+    }
+
+
+    // Merge the memory table down into the tree, completing any required other
+    // merges to make room for it.
+    inline void merge_buffer(gsl_rng *rng) {
+        auto buffer = get_buffer();
+
+        if (!can_merge_with(0, buffer->get_record_count())) {
+            merge_down(0, rng);
+        }
+
+        merge_buffer_into_l0(buffer, rng);
+        enforce_delete_maximum(0, rng);
+
+        buffer->tshardcate();
+        return;
+    }
+
+    /*
+     * Merge the specified level down into the tree. The level index must be
+     * non-negative (i.e., this function cannot be used to merge the buffer). This
+     * routine will recursively perform any necessary merges to make room for the 
+     * specified level.
+     */
+    inline void merge_down(level_index idx, gsl_rng *rng) {
+        level_index merge_base_level = find_mergable_level(idx);
+        if (merge_base_level == -1) {
+            merge_base_level = grow();
+        }
+
+        for (level_index i=merge_base_level; i>idx; i--) {
+            merge_levels(i, i-1, rng);
+            enforce_delete_maximum(i, rng);
+        }
+
+        return;
+    }
+
+    /*
+     * Find the first level below the level indicated by idx that
+     * is capable of sustaining a merge operation and return its
+     * level index. If no such level exists, returns -1. Also
+     * returns -1 if idx==0, and no such level exists, to simplify
+     * the logic of the first merge.
+     */
+    inline level_index find_mergable_level(level_index idx, MutableBuffer<K,V,W> *buffer=nullptr) {
+
+        if (idx == 0 && m_levels.size() == 0) return -1;
+
+        bool level_found = false;
+        bool disk_level;
+        level_index merge_level_idx;
+
+        size_t incoming_rec_cnt = get_level_record_count(idx, buffer);
+        for (level_index i=idx+1; i<=m_last_level_idx; i++) {
+            if (can_merge_with(i, incoming_rec_cnt)) {
+                return i;
+            }
+
+            incoming_rec_cnt = get_level_record_count(i);
+        }
+
+        return -1;
+    }
+
+    /*
+     * Merge the level specified by incoming level into the level specified
+     * by base level. The two levels should be sequential--i.e. no levels
+     * are skipped in the merge process--otherwise the tombstone ordering
+     * invariant may be violated by the merge operation.
+     */
+    inline void merge_levels(level_index base_level, level_index incoming_level, gsl_rng *rng) {
+        // merging two memory levels
+        if (LSM_LEVELING) {
+            auto tmp = m_levels[base_level];
+            m_levels[base_level] = InternalLevel<K,V,W>::merge_levels(m_levels[base_level], m_levels[incoming_level],
+                                                                          DELETE_TAGGING, rng);
+            mark_as_unused(tmp);
+        } else {
+            m_levels[base_level]->append_merged_shards(m_levels[incoming_level], rng);
+        }
+
+        mark_as_unused(m_levels[incoming_level]);
+        m_levels[incoming_level] = new InternalLevel<K,V,W>(incoming_level, (LSM_LEVELING) ? 1 : m_scale_factor, DELETE_TAGGING);
+    }
+
+
+    inline void merge_buffer_into_l0(MutableBuffer<K,V,W> *buffer, gsl_rng *rng) {
+        assert(m_levels[0]);
+        if (LSM_LEVELING) {
+            // FIXME: Kludgey implementation due to interface constraints.
+            auto old_level = m_levels[0];
+            auto temp_level = new InternalLevel<K,V,W>(0, 1, DELETE_TAGGING);
+            temp_level->append_mem_table(buffer, rng);
+            auto new_level = InternalLevel<K,V,W>::merge_levels(old_level, temp_level, DELETE_TAGGING, rng);
+
+            m_levels[0] = new_level;
+            delete temp_level;
+            mark_as_unused(old_level);
+        } else {
+            m_levels[0]->append_mem_table(buffer, rng);
+        }
+    }
+
+    /*
+     * Mark a given memory level as no-longer in use by the tree. For now this
+     * will just free the level. In future, this will be more complex as the
+     * level may not be able to immediately be deleted, depending upon who
+     * else is using it.
+     */ 
+    inline void mark_as_unused(InternalLevel<K,V,W> *level) {
+        delete level;
+    }
+
+    /*
+     * Check the tombstone proportion for the specified level and
+     * if the limit is exceeded, forcibly merge levels until all
+     * levels below idx are below the limit.
+     */
+    inline void enforce_delete_maximum(level_index idx, gsl_rng *rng) {
+        long double ts_prop = (long double) m_levels[idx]->get_tombstone_count() / (long double) calc_level_record_capacity(idx);
+
+        if (ts_prop > (long double) m_max_delete_prop) {
+            merge_down(idx, rng);
+        }
+
+        return;
+    }
+
+    inline void enforce_rejection_rate_maximum(gsl_rng *rng) {
+        if (m_levels.size() == 0) {
+            return;
+        }
+
+        for (size_t i=0; i<m_last_level_idx; i++) {
+            if (m_levels[i]) {
+                double ratio = m_levels[i]->get_rejection_rate();
+                if (ratio > m_max_rejection_rate) {
+                    merge_down(i, rng);
+                }
+            }
+        } 
+    }
+
+    /*
+     * Assume that level "0" should be larger than the buffer. The buffer
+     * itself is index -1, which should return simply the buffer capacity.
+     */
+    inline size_t calc_level_record_capacity(level_index idx) {
+        return get_buffer()->get_capacity() * pow(m_scale_factor, idx+1);
+    }
+
+    /*
+     * Returns the actual number of records present on a specified level. An
+     * index value of -1 indicates the memory table. Can optionally pass in
+     * a pointer to the memory table to use, if desired. Otherwise, there are
+     * no guarantees about which buffer will be accessed if level_index is -1.
+     */
+    inline size_t get_level_record_count(level_index idx, MutableBuffer<K,V,W> *buffer=nullptr) {
+        assert(idx >= -1);
+        if (idx == -1) {
+            return (buffer) ? buffer->get_record_count() : get_buffer()->get_record_count();
+        }
+
+        return (m_levels[idx]) ? m_levels[idx]->get_record_cnt() : 0;
+    }
+
+    /*
+     * Determines if the specific level can merge with another record containing
+     * incoming_rec_cnt number of records. The provided level index should be 
+     * non-negative (i.e., not refer to the buffer) and will be automatically
+     * translated into the appropriate index into either the disk or memory level
+     * vector.
+     */
+    inline bool can_merge_with(level_index idx, size_t incoming_rec_cnt) {
+        if (idx>= m_levels.size() || !m_levels[idx]) {
+            return false;
+        }
+
+        if (LSM_LEVELING) {
+            return m_levels[idx]->get_record_cnt() + incoming_rec_cnt <= calc_level_record_capacity(idx);
+        } else {
+            return m_levels[idx]->get_shard_count() < m_scale_factor;
+        }
+
+        // unreachable
+        assert(true);
+    }
+};
+
+}
+