comparator_db_test to cover more irregular comparators

Summary:
comparator_db_test now adds verification for three more comparators:
(1) one that store double as string
(2) one that cast uint64 to string
(3) one that concatenate two strings, prefixing their sizes.
(4) one that order by hash of the string

Test Plan:
Run ./comparator_db_test

Reviewers: ljin, yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D27927

db/comparator_db_test.cc

@@ -9,6 +9,7 @@
 
 #include "rocksdb/db.h"
 #include "rocksdb/env.h"
+#include "util/hash.h"
 #include "util/testharness.h"
 #include "util/testutil.h"
 #include "utilities/merge_operators.h"
@@ -165,6 +166,84 @@ void DoRandomIteraratorTest(DB* db, std::vector<std::string> source_strings,
     is_valid = iter->Valid();
   }
 }
+
+class DoubleComparator : public Comparator {
+ public:
+  DoubleComparator() {}
+
+  virtual const char* Name() const { return "DoubleComparator"; }
+
+  virtual int Compare(const Slice& a, const Slice& b) const {
+    double da = std::stod(a.ToString());
+    double db = std::stod(b.ToString());
+    if (da == db) {
+      return a.compare(b);
+    } else if (da > db) {
+      return 1;
+    } else {
+      return -1;
+    }
+  }
+  virtual void FindShortestSeparator(std::string* start,
+                                     const Slice& limit) const {}
+
+  virtual void FindShortSuccessor(std::string* key) const {}
+};
+
+class HashComparator : public Comparator {
+ public:
+  HashComparator() {}
+
+  virtual const char* Name() const { return "HashComparator"; }
+
+  virtual int Compare(const Slice& a, const Slice& b) const {
+    uint32_t ha = Hash(a.data(), a.size(), 66);
+    uint32_t hb = Hash(b.data(), b.size(), 66);
+    if (ha == hb) {
+      return a.compare(b);
+    } else if (ha > hb) {
+      return 1;
+    } else {
+      return -1;
+    }
+  }
+  virtual void FindShortestSeparator(std::string* start,
+                                     const Slice& limit) const {}
+
+  virtual void FindShortSuccessor(std::string* key) const {}
+};
+
+class TwoStrComparator : public Comparator {
+ public:
+  TwoStrComparator() {}
+
+  virtual const char* Name() const { return "TwoStrComparator"; }
+
+  virtual int Compare(const Slice& a, const Slice& b) const {
+    assert(a.size() >= 2);
+    assert(b.size() >= 2);
+    size_t size_a1 = static_cast<size_t>(a[0]);
+    size_t size_b1 = static_cast<size_t>(b[0]);
+    size_t size_a2 = static_cast<size_t>(a[1]);
+    size_t size_b2 = static_cast<size_t>(b[1]);
+    assert(size_a1 + size_a2 + 2 == a.size());
+    assert(size_b1 + size_b2 + 2 == b.size());
+
+    Slice a1 = Slice(a.data() + 2, size_a1);
+    Slice b1 = Slice(b.data() + 2, size_b1);
+    Slice a2 = Slice(a.data() + 2 + size_a1, size_a2);
+    Slice b2 = Slice(b.data() + 2 + size_b1, size_b2);
+
+    if (a1 != b1) {
+      return a1.compare(b1);
+    }
+    return a2.compare(b2);
+  }
+  virtual void FindShortestSeparator(std::string* start,
+                                     const Slice& limit) const {}
+
+  virtual void FindShortSuccessor(std::string* key) const {}
+};
 }  // namespace
 
 class ComparatorDBTest {
@@ -255,6 +334,101 @@ TEST(ComparatorDBTest, SimpleSuffixReverseComparator) {
     DoRandomIteraratorTest(GetDB(), source_strings, &rnd, 30, 600, 66);
   }
 }
+
+TEST(ComparatorDBTest, Uint64Comparator) {
+  SetOwnedComparator(test::Uint64Comparator());
+
+  for (int rnd_seed = 301; rnd_seed < 316; rnd_seed++) {
+    Options* opt = GetOptions();
+    opt->comparator = comparator;
+    DestroyAndReopen();
+    Random rnd(rnd_seed);
+    Random64 rnd64(rnd_seed);
+
+    std::vector<std::string> source_strings;
+    // Randomly generate source keys
+    for (int i = 0; i < 100; i++) {
+      uint64_t r = rnd64.Next();
+      std::string str;
+      str.resize(8);
+      memcpy(&str[0], static_cast<void*>(&r), 8);
+      source_strings.push_back(str);
+    }
+
+    DoRandomIteraratorTest(GetDB(), source_strings, &rnd, 200, 1000, 66);
+  }
+}
+
+TEST(ComparatorDBTest, DoubleComparator) {
+  SetOwnedComparator(new DoubleComparator());
+
+  for (int rnd_seed = 301; rnd_seed < 316; rnd_seed++) {
+    Options* opt = GetOptions();
+    opt->comparator = comparator;
+    DestroyAndReopen();
+    Random rnd(rnd_seed);
+
+    std::vector<std::string> source_strings;
+    // Randomly generate source keys
+    for (int i = 0; i < 100; i++) {
+      uint32_t r = rnd.Next();
+      uint32_t divide_order = rnd.Uniform(8);
+      double to_divide = 1.0;
+      for (uint32_t j = 0; j < divide_order; j++) {
+        to_divide *= 10.0;
+      }
+      source_strings.push_back(std::to_string(r / to_divide));
+    }
+
+    DoRandomIteraratorTest(GetDB(), source_strings, &rnd, 200, 1000, 66);
+  }
+}
+
+TEST(ComparatorDBTest, HashComparator) {
+  SetOwnedComparator(new HashComparator());
+
+  for (int rnd_seed = 301; rnd_seed < 316; rnd_seed++) {
+    Options* opt = GetOptions();
+    opt->comparator = comparator;
+    DestroyAndReopen();
+    Random rnd(rnd_seed);
+
+    std::vector<std::string> source_strings;
+    // Randomly generate source keys
+    for (int i = 0; i < 100; i++) {
+      source_strings.push_back(test::RandomKey(&rnd, 8));
+    }
+
+    DoRandomIteraratorTest(GetDB(), source_strings, &rnd, 200, 1000, 66);
+  }
+}
+
+TEST(ComparatorDBTest, TwoStrComparator) {
+  SetOwnedComparator(new TwoStrComparator());
+
+  for (int rnd_seed = 301; rnd_seed < 316; rnd_seed++) {
+    Options* opt = GetOptions();
+    opt->comparator = comparator;
+    DestroyAndReopen();
+    Random rnd(rnd_seed);
+
+    std::vector<std::string> source_strings;
+    // Randomly generate source keys
+    for (int i = 0; i < 100; i++) {
+      std::string str;
+      uint32_t size1 = rnd.Uniform(8);
+      uint32_t size2 = rnd.Uniform(8);
+      str.append(1, static_cast<char>(size1));
+      str.append(1, static_cast<char>(size2));
+      str.append(test::RandomKey(&rnd, size1));
+      str.append(test::RandomKey(&rnd, size2));
+      source_strings.push_back(str);
+    }
+
+    DoRandomIteraratorTest(GetDB(), source_strings, &rnd, 200, 1000, 66);
+  }
+}
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) { return rocksdb::test::RunAllTests(); }