Support both pre- and post-#83 SDBM key formats

lib/gel/db.rb

@@ -194,11 +194,12 @@ def [](key)
 
     if value =~ /\A~(\d+)\z/
       value = $1.to_i.times.map do |idx|
-        @sdbm["#{key}~#{idx}"]
+        @sdbm["#{key}~#{idx}"] || @sdbm["#{key}---#{idx}"] ||
+          raise("missing key: " + "#{key}~#{idx}".inspect)
       end.join
     end
 
-    return Marshal.load(value)
+    Marshal.load(value)
   end
 
 
@@ -211,21 +212,34 @@ def [](key)
   # amount of extra values stored to hold the split string. This amount is
   # determined by string size split by the arbitrary limit imposed by SDBM
   def []=(key, value)
-    return unless value && key
+    raise if key.nil?
+
+    if value.nil?
+      delete key
+      return
+    end
+
+    key = key.to_s
 
     dump = Marshal.dump(value)
     slicesize = SDBM_PAIRMAX - key.length - 3 # "#{key}~#{i}" where i <= 99
     slices = dump.length / slicesize + 1
 
+    if (existing_value = @sdbm[key]) && existing_value =~ /\A~(\d+)\z/ && $1.to_i > slices
+      $1.to_i.times do |idx|
+        @sdbm.delete("#{key}~#{idx}") || @sdbm.delete("#{key}---#{idx}")
+      end
+    end
+
     if slices > 1
-      slices.times.map do |idx|
-        slicekey = "#{key.to_s}~#{idx}"
+      slices.times do |idx|
+        slicekey = "#{key}~#{idx}"
         slicedump = dump.slice!(0, slicesize)
         @sdbm[slicekey] = slicedump
       end
-      @sdbm["#{key.to_s}"] = "~#{slices}"
+      @sdbm[key] = "~#{slices}"
     else
-      @sdbm[key.to_s] = dump
+      @sdbm[key] = dump
     end
   end
 
@@ -235,11 +249,11 @@ def delete(key)
 
     if value =~ /\A~(\d+)\z/
       $1.to_i.times.map do |idx|
-        @sdbm.delete("#{key}~#{idx}")
+        @sdbm.delete("#{key}~#{idx}") || @sdbm.delete("#{key}---#{idx}")
       end.join
     end
 
-    return Marshal.load(value)
+    Marshal.load(value)
   end
 end
 

test/db_test.rb

@@ -36,4 +36,37 @@ def test_sdbm_store_value_retrieval
       assert_equal db['test'], hash_string
     end
   end
+
+  def test_previous_multikey_format
+    skip unless defined? ::SDBM
+    Dir.mktmpdir do |dir|
+      db = Gel::DB::SDBM.new(dir, "test-store")
+
+      sdbm = db.instance_variable_get(:@sdbm)
+      sdbm["test"] = "~4"
+      sdbm["test---0"] = "\x04\x08\"\x09a"
+      sdbm["test---1"] = "b"
+      sdbm["test---2"] = "c"
+      sdbm["test---3"] = "d"
+
+      assert_equal "abcd", db["test"]
+
+      assert_equal %w(test test---0 test---1 test---2 test---3), sdbm.keys.sort
+
+      db["test"] = "short"
+
+      assert_equal %w(test), sdbm.keys.sort
+
+      sdbm["test"] = "~4"
+      sdbm["test---0"] = "\x04\x08\"\x09a"
+      sdbm["test---1"] = "b"
+      sdbm["test---2"] = "c"
+      sdbm["test---3"] = "d"
+
+      long_string = "*" * (Gel::DB::SDBM::SDBM_PAIRMAX + 200)
+      db["test"] = long_string
+
+      assert_equal %w(test test~0 test~1), sdbm.keys.sort
+    end
+  end
 end