Naive iterator

Author: benesch

GNUmakefile.in

@@ -88,7 +88,7 @@ stamp-h: config.h.in config.status
 	echo > stamp-h
 
 clean:
-	rm -f mtd mtclient mttest test_string test_atomics *.o libjson.a
+	rm -f mtd mtclient mttest scantest test_string test_atomics *.o libjson.a
 	rm -rf .deps
 
 DEPFILES := $(wildcard $(DEPSDIR)/*.d)

masstree.hh

@@ -60,6 +60,7 @@ class basic_table {
     typedef typename P::threadinfo_type threadinfo;
     typedef unlocked_tcursor<P> unlocked_cursor_type;
     typedef tcursor<P> cursor_type;
+    typedef std::pair<Str, value_type> itvalue_type;
 
     inline basic_table();
 
@@ -76,6 +77,11 @@ class basic_table {
     template <typename F>
     int rscan(Str firstkey, bool matchfirst, F& scanner, threadinfo& ti) const;
 
+    class iterator;
+    iterator begin(threadinfo& ti);
+    iterator iterate_from(Str firstkey, threadinfo& ti);
+    iterator end(threadinfo& ti);
+
     template <typename F>
     inline int modify(Str key, F& f, threadinfo& ti);
     template <typename F>

masstree_iterator.hh

@@ -0,0 +1,240 @@
+/* Masstree
+ * Eddie Kohler, Yandong Mao, Robert Morris
+ * Copyright (c) 2012-2014 President and Fellows of Harvard College
+ * Copyright (c) 2012-2014 Massachusetts Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, subject to the conditions
+ * listed in the Masstree LICENSE file. These conditions include: you must
+ * preserve this copyright notice, and you cannot mention the copyright
+ * holders in advertising related to the Software without their permission.
+ * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
+ * notice is a summary of the Masstree LICENSE file; the license in that file
+ * is legally binding.
+ */
+#ifndef MASSTREE_ITERATOR_HH
+#define MASSTREE_ITERATOR_HH
+#include "masstree_scan.hh"
+
+namespace Masstree {
+template <typename P>
+class basic_table<P>::iterator
+    : std::iterator<std::forward_iterator_tag, itvalue_type> {
+    typedef typename P::ikey_type ikey_type;
+    typedef typename node_type::key_type key_type;
+    typedef typename node_type::leaf_type::leafvalue_type leafvalue_type;
+    typedef typename node_type::nodeversion_type nodeversion_type;
+    typedef typename leaf_type::permuter_type permuter_type;
+    typedef typename leaf_type::bound_type bound_type;
+
+  public:
+    iterator(basic_table<P>* table, threadinfo* ti, Str firstkey = "");
+    static iterator make_end(basic_table<P>* table, threadinfo *ti);
+
+    itvalue_type& operator*() { return pair_; };
+    itvalue_type* operator->() { return &pair_; };
+    bool operator==(iterator& rhs) { return (end_ == rhs.end_) && (end_ || ka_.compare(rhs.ka_) == 0); };
+    bool operator!=(iterator& rhs) { return !(*this == rhs); };
+    bool operator<(iterator& rhs) { return (!end_ && rhs.end_) || ka_.compare(rhs.ka_) < 0; };
+    bool operator<=(iterator& rhs) { return *this < rhs || *this == rhs; };
+    iterator operator++() { advance(); return *this; };
+    iterator operator++(int) { iterator it = *this; advance(); return it; };
+
+  private:
+    basic_table<P>* table_;
+    threadinfo* ti_;
+    key_type ka_;
+    itvalue_type pair_;
+    bool emit_equal_;
+    bool end_;
+    union {
+        ikey_type x[(MASSTREE_MAXKEYLEN + sizeof(ikey_type) - 1)/sizeof(ikey_type)];
+        char s[MASSTREE_MAXKEYLEN];
+    } keybuf_;
+
+    void advance(bool allow_next = true);
+
+
+    // Debugging support.
+    int id_;
+    static int count_;
+
+    void dprintf(const char *format, ...) {
+        va_list args;
+        va_start(args, format);
+        fprintf(stderr, "it%d: ", id_);
+        vfprintf(stderr, format, args);
+        va_end(args);
+    }
+};
+
+template <typename P> int basic_table<P>::iterator::count_ = 0;
+
+template <typename P>
+basic_table<P>::iterator::iterator(basic_table<P>* table, threadinfo* ti, Str firstkey)
+    : table_(table), ti_(ti), emit_equal_(true), end_(false), id_(count_++) {
+    masstree_precondition(firstkey.len <= (int) sizeof(keybuf_));
+    memcpy(keybuf_.s, firstkey.s, firstkey.len);
+    ka_ = key_type(keybuf_.s, firstkey.len);
+
+    advance();
+};
+
+template <typename P>
+typename basic_table<P>::iterator
+basic_table<P>::iterator::make_end(basic_table<P>* table, threadinfo *ti) {
+    iterator it = iterator(table, ti);
+    it.end_ = true;
+    return it;
+}
+
+template <typename P>
+void
+basic_table<P>::iterator::advance(bool allow_next) {
+    key_indexed_position kx;
+    int keylenx;
+    char suffixbuf[MASSTREE_MAXKEYLEN];
+    Str suffix;
+    leafvalue_type entry;
+    leaf_type* n;
+    nodeversion_type v;
+    permuter_type perm;
+    bool found = false;
+    node_type* root;
+
+ retry:
+    keylenx = 0;
+    root = table_->root();
+    ka_.unshift_all();
+
+    // Find initial.
+    // XXX The control flow of this loop is incomprehensible.
+    while (!found) {
+        n = root->reach_leaf(ka_, v, *ti_);
+
+        if (v.deleted())
+            goto retry;
+        n->prefetch();
+        perm = n->permutation();
+
+        kx = bound_type::lower(ka_, *n);
+        if (kx.p >= 0) {
+            keylenx = n->keylenx_[kx.p];
+            fence();
+            entry = n->lv_[kx.p];
+            entry.prefetch(keylenx);
+            if (n->keylenx_has_ksuf(keylenx)) {
+                suffix = n->ksuf(kx.p);
+                memcpy(suffixbuf, suffix.s, suffix.len);
+                suffix.s = suffixbuf;
+            }
+        }
+        if (n->has_changed(v)) {
+            ti_->mark(tc_leaf_retry);
+            n = n->advance_to_key(ka_, v, *ti_);
+            goto retry;
+        }
+
+        if (kx.p >= 0) {
+            if (n->keylenx_is_layer(keylenx)) {
+                root = entry.layer();
+                ka_.shift();
+                continue;
+            } else if (n->keylenx_has_ksuf(keylenx)) {
+                int ksuf_compare = suffix.compare(ka_.suffix());
+                if (ksuf_compare > 0 || (ksuf_compare == 0 && emit_equal_)) {
+                    int keylen = ka_.assign_store_suffix(suffix);
+                    ka_.assign_store_length(keylen);
+                    found = true;
+                }
+            }
+            found = emit_equal_;
+        }
+        break;
+    }
+
+    // Find next.
+    int kp;
+    int ki = kx.i + 1;
+    while (!found) {
+        if (v.deleted())
+            goto retry;
+
+        kp = unsigned(ki) < unsigned(perm.size()) ? perm[ki] : -1;
+        if (kp >= 0) {
+            ikey_type ikey = n->ikey0_[kp];
+            int keylenx = n->keylenx_[kp];
+            int keylen = keylenx;
+            fence();
+            entry = n->lv_[kp];
+            entry.prefetch(keylenx);
+            if (n->keylenx_has_ksuf(keylenx))
+                keylen = ka_.assign_store_suffix(n->ksuf(kp));
+
+            if (n->has_changed(v))
+                goto retry;
+            else if (ka_.compare(ikey, keylenx) >= 0) {
+                ki++;
+                continue;
+            }
+
+            ka_.assign_store_ikey(ikey);
+            if (n->keylenx_is_layer(keylenx)) {
+                root = entry.layer();
+                n = root->reach_leaf(ka_, v, *ti_);
+                ka_.shift();
+                goto changed;
+            } else {
+                ka_.assign_store_length(keylen);
+                found = true;
+                break;
+            }
+        }
+
+        if (!n->has_changed(v)) {
+            n = n->safe_next();
+            if (!n) {
+                if (allow_next) {
+                    ka_.unshift();
+                    ka_.assign_store_length(ka_.ikey_size);
+                    emit_equal_ = true;
+                    advance(false);
+                    return;
+                } else {
+                    end_ = true;
+                    return;
+                }
+            }
+        }
+
+     changed:
+        n->prefetch();
+        v = n->stable();
+        perm = n->permutation();
+        ki = bound_type::lower(ka_, *n).i;
+    }
+
+    pair_ = itvalue_type(ka_, entry.value());
+    emit_equal_ = false;
+}
+
+template <typename P>
+typename basic_table<P>::iterator
+basic_table<P>::begin(threadinfo& ti) {
+    return iterator(this, &ti);
+}
+
+template <typename P>
+typename basic_table<P>::iterator
+basic_table<P>::end(threadinfo& ti) {
+    return iterator::make_end(this, &ti);
+}
+
+template <typename P>
+typename basic_table<P>::iterator
+basic_table<P>::iterate_from(Str firstkey, threadinfo& ti) {
+    return iterator(this, &ti, firstkey);
+}
+}
+#endif

query_masstree.cc

@@ -19,6 +19,7 @@
 #include "masstree_tcursor.hh"
 #include "masstree_get.hh"
 #include "masstree_insert.hh"
+#include "masstree_iterator.hh"
 #include "masstree_split.hh"
 #include "masstree_remove.hh"
 #include "masstree_scan.hh"
@@ -413,6 +414,45 @@ void query_table<P>::test(threadinfo& ti) {
     // XXX destroy tree
 }
 
+template <typename P>
+void query_table<P>::iterator_test(threadinfo& ti) {
+    typedef typename basic_table<P>::iterator iterator;
+
+    query_table<P> t;
+    t.initialize(ti);
+    query<row_type> q;
+
+    const char * const values[] = {
+        "", "0", "1", "10", "100000000",                        // 0-4
+        "1000000001", "1000000002", "2", "20", "200000000",     // 5-9
+        "aaaaaaaaaaaaaaaaaaaaaaaaaa",                           // 10
+        "aaaaaaaaaaaaaaabbbb", "aaaaaaaaaaaaaaabbbc", "aaaaaaaaaxaaaaabbbc", "b", "c", "d", "e", "f", "g", "h", "i", "j",
+        "kkkkkkkk\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF" "a",
+        "kkkkkkkk\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF" "b",
+        "xxxxxxxxy"
+    };
+    const char *values_copy[arraysize(values)];
+    memcpy(values_copy, values, sizeof(values));
+
+    for (int i = arraysize(values); i > 0; --i) {
+        int x = rand() % i;
+        q.run_replace(t.table(), Str(values_copy[x]), Str(values_copy[x]), ti);
+        values_copy[x] = values_copy[i - 1];
+    }
+
+    const char * const * pos = values;
+    iterator itend = t.table_.end(ti);
+    for (iterator it = t.table_.begin(ti); it != itend; it++) {
+        Str key = it->first;
+        if ((int) strlen(*pos) != key.len || memcmp(*pos, key.s, key.len) != 0) {
+            fprintf(stderr, "scan encountered \"%.*s\", expected \"%s\"\n", key.len, key.s, *pos);
+            assert((int) strlen(*pos) == key.len && memcmp(*pos, key.s, key.len) == 0);
+        }
+        fprintf(stderr, "scan %.*s\n", key.len, key.s);
+        pos++;
+    }
+}
+
 template <typename P>
 void query_table<P>::print(FILE *f, int indent) const {
     table_.print(f, indent);

query_masstree.hh

@@ -61,6 +61,7 @@ class query_table {
     void print(FILE* f, int indent) const;
 
     static void test(threadinfo& ti);
+    static void iterator_test(threadinfo& ti);
 
     static const char* name() {
         return "mb";

scantest.cc

@@ -10,9 +10,21 @@ kvtimestamp_t initial_timestamp;
 int
 main(int argc, char *argv[])
 {
-    (void) argc;
-    (void) argv;
+    if (argc != 2) {
+        fprintf(stderr, "usage: %s <callback|iterator>\n", argv[0]);
+        return 1;
+    }
 
     threadinfo* ti = threadinfo::make(threadinfo::TI_MAIN, -1);
-    default_table::test(*ti);
+
+    if (strcmp(argv[1], "callback") == 0)
+        default_table::test(*ti);
+    else if (strcmp(argv[1], "iterator") == 0)
+        default_table::iterator_test(*ti);
+    else {
+        fprintf(stderr, "fatal: unknown test\n");
+        return 1;
+    }
+
+    return 0;
 }