RUBY-319: Support reading decimals in scientific notation with positive exponent

Author: stamhankar999

CHANGELOG.md

@@ -1,4 +1,6 @@
 # master
+Bug Fixes:
+* [RUBY-319](https://datastax-oss.atlassian.net/browse/RUBY-319) Support reading decimals in scientific notation with positive exponent.
 
 # 3.2.1
 

lib/cassandra/protocol/cql_byte_buffer.rb

@@ -53,24 +53,30 @@ def read_varint(len = bytesize, signed = true)
       end
 
       def read_decimal(len = bytesize)
-        size = read_signed_int
+        scale = read_signed_int
         number_string = read_varint(len - 4).to_s
-        if number_string.length <= size
-          if number_string.start_with?(MINUS)
-            number_string = number_string[1, number_string.length - 1]
-            fraction_string = MINUS + ZERO << DECIMAL_POINT
+        if scale < 0
+          # Special case where the actual scale is positive; scale in the protocol is actually negative of
+          # reality.
+          BigDecimal.new(number_string + '0' * -scale)
+        else
+          if number_string.length <= scale
+            if number_string.start_with?(MINUS)
+              number_string = number_string[1, number_string.length - 1]
+              fraction_string = MINUS + ZERO << DECIMAL_POINT
+            else
+              fraction_string = ZERO + DECIMAL_POINT
+            end
+            (scale - number_string.length).times { fraction_string << ZERO }
+            fraction_string << number_string
           else
-            fraction_string = ZERO + DECIMAL_POINT
+            fraction_string = number_string[0, number_string.length - scale]
+            fraction_string << DECIMAL_POINT
+            fraction_string <<
+              number_string[number_string.length - scale, number_string.length]
           end
-          (size - number_string.length).times { fraction_string << ZERO }
-          fraction_string << number_string
-        else
-          fraction_string = number_string[0, number_string.length - size]
-          fraction_string << DECIMAL_POINT
-          fraction_string <<
-            number_string[number_string.length - size, number_string.length]
+          BigDecimal.new(fraction_string)
         end
-        BigDecimal.new(fraction_string)
       rescue Errors::DecodingError => e
         raise Errors::DecodingError, e.message, e.backtrace
       end

lib/cassandra/protocol/cql_protocol_handler.rb

@@ -270,9 +270,7 @@ def initialize(request, timeout, scheduler)
         def time_out!
           unless future.completed?
             @timed_out = true
-            # rubocop:disable Style/SignalException
             fail(Errors::TimeoutError.new('Timed out'))
-            # rubocop:enable Style/SignalException
           end
         end
 

spec/cassandra/protocol/cql_byte_buffer_spec.rb

@@ -102,6 +102,16 @@ module Protocol
           buffer.read_decimal.should == BigDecimal.new('-0.031108612692221094')
         end
 
+        it 'decodes a decimal with negative scale' do
+          buffer = described_class.new("\xff\xff\xff\xfa\x0a")
+          buffer.read_decimal.should == BigDecimal.new('10000000')
+        end
+
+        it 'decodes a negative decimal with negative scale' do
+          buffer = described_class.new("\xff\xff\xff\xf9\xfd")
+          buffer.read_decimal.should == BigDecimal.new('-30000000')
+        end
+
         it 'consumes the bytes' do
           buffer << 'HELLO'
           buffer.read_decimal(buffer.length - 5)