Approach to reduce Cyclometic Complexity
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04-06-2021 - |
Вопрос
I work on a big java project(mobile application), and got the "thankful" job to review and optimize/refactore code, because of the poor performance(high complexity). Note: I'm totally new to Java(my background is C/C++), therefore I applogize for any dumb question. The first thing I did, was to use Findbugs and fix all reported issues. Afterwards I used the metric tool Understand to get an overview, which methods have a high cyclomatic complexity. Unfortunately there were a lot of methods with a cyclometic complexity above the 2^20 range :-( And one of them is where I would need some help or good ideas...
Short description:
For the communication with a server data has to be serialized. There is no Serializable interface available on this mobile framework.
Therefore, the colleague, who wrote all of the code(alone) implemented a Serializable interface containing one method called toByteArray()
.
E.g., the class Customer
:
class Customer
{
Address address;
AttributeCollection attributes;
LocationCollection locations;
int recId;
int recStatus;
DateTime recCreated;
String recCreatedBy;
String recCreatedByProg;
DateTime recChanged;
String recChangedBy;
String recChangedByProg;
int refAddressesId;
int refMandatorsId;
CustomerPropertyUsage usage;
/**
* Serialize the properties of a class into a byte array.
* @param destData Byte array, where the serialized data should be stored. Minimum 2 bytes.
* @param serializationIndex Offset within the passed byte array, from which the serialized data of the class
* should be entered. The offset is increased by the registered number of bytes so that after this method the
* next call points to the serialized data subsequent byte.
*/
void toByteArray(byte[] destData, IntClass serializationIndex)
{
if (this.address == null)
this.usage.value &= ~CustomerPropertyUsage.ADDRESS;
if (this.attributes == null)
this.usage.value &= ~CustomerPropertyUsage.ATTRIBUTES;
if (this.locations == null)
this.usage.value &= ~CustomerPropertyUsage.LOCATIONS;
this.usage.toByteArray(destData, serializationIndex);
CatrString catrString = null;
if ((this.usage.value & CustomerPropertyUsage.RECORD_HEADER) != CustomerPropertyUsage.NONE)
{
// Call static method getBytes from SerializationHelper class
SerializationHelper.getBytes(this.recId, 4, destData, serializationIndex.value);
serializationIndex.value += 4;
SerializationHelper.getBytes(this.recStatus, 4, destData, serializationIndex.value);
serializationIndex.value += 4;
// recChanged is a DateTime object. For the serialization we need minimum a 7 bytes array,
// Call method toByteArray() from DateTime class.
this.recChanged.toByteArray(destData, serializationIndex);
// call toByteArray of CatrString class
catrString = new CatrString(this.recChangedBy);
catrString.toByteArray(destData, serializationIndex);
catrString.setValue(this.recChangedByProg);
catrString.toByteArray(destData, serializationIndex);
// Same as recChanged
this.recCreated.toByteArray(destData, serializationIndex);
catrString = new CatrString(this.recCreatedBy);
catrString.toByteArray(destData, serializationIndex);
catrString.setValue(this.recCreatedByProg);
catrString.toByteArray(destData, serializationIndex);
SerializationHelper.getBytes(this.refAddressesId, 4, destData, serializationIndex.value);
serializationIndex.value += 4;
SerializationHelper.getBytes(this.refMandatorsId, 4, destData, serializationIndex.value);
serializationIndex.value += 4;
}
if (next property...)
{
... Serialization ...
}
if (next property...)
{
... Serialization ...
}
}
}
To keep the GPRS dues low, the server sets a value in this.usage.value and therefore only a specific property will be serialized and transmitted back to the server --> transmitted messages are small. This approach creates a lot of if-cases, depending on how much properties are in the class and therefore the path count gets higher and higher. I think that's not a beatiful solution but it's okay. What I would like to change is the serialization calls inside the if-cases. At the moment they look like this:
---- class SerializationHelper ----
static void getBytes(long valueToConvert, int numOfBytesToConvert, byte[] destinationBytes, int destinationBytesOffset)
{
destinationBytes[destinationBytesOffset] = (byte)(valueToConvert & 0x000000FF);
destinationBytes[destinationBytesOffset + 1] = (byte)((valueToConvert & 0x0000FF00) >> 8);
if (numOfBytesToConvert > 2)
{
destinationBytes[destinationBytesOffset + 2] = (byte)((valueToConvert & 0x00FF0000) >> 16);
destinationBytes[destinationBytesOffset + 3] = (byte)((valueToConvert & 0xFF000000) >> 24);
if (numOfBytesToConvert > 4)
{
destinationBytes[destinationBytesOffset + 4] = (byte)((valueToConvert & 0x000000FF00000000L) >> 32);
destinationBytes[destinationBytesOffset + 5] = (byte)((valueToConvert & 0x0000FF0000000000L) >> 40);
destinationBytes[destinationBytesOffset + 6] = (byte)((valueToConvert & 0x00FF000000000000L) >> 48);
destinationBytes[destinationBytesOffset + 7] = (byte)((valueToConvert & 0xFF00000000000000L) >> 56);
}
}
}
---- class CatrString ----
void toByteArray(byte[] destData, IntClass serializationIndex)
{
// Number of unicode characters
SerializationHelper.getBytes(this.textLength, 2, destData, serializationIndex.value);
serializationIndex.value += 2;
// Text UTF-16 unicode characters
for (int charIndex = 0; charIndex < this.textLength; charIndex++)
{
destData[serializationIndex.value] = (byte)(this.charCodes[charIndex] & 0x00FF);
serializationIndex.value++;
destData[serializationIndex.value] = (byte)((this.charCodes[charIndex] & 0xFF00) >> 8);
serializationIndex.value++;
}
// Code End of string as UTF-16 unicode character
destData[serializationIndex.value] = 0x00;
serializationIndex.value++;
destData[serializationIndex.value] = 0x00;
serializationIndex.value++;
}
---- class DateTime ----
void toByteArray(byte[] destData, IntClass serializationIndex)
{
destData[serializationIndex.value + 0] = (byte) (m_year % 0x0100); // year low-Byte.
destData[serializationIndex.value + 1] = (byte) (m_year / 0x0100); // year high-Byte.
destData[serializationIndex.value + 2] = (byte) (m_month);
destData[serializationIndex.value + 3] = (byte) m_day;
destData[serializationIndex.value + 4] = (byte) m_hour;
destData[serializationIndex.value + 5] = (byte) m_minute;
destData[serializationIndex.value + 6] = (byte) m_second;
serializationIndex.value += 7;
}
It should be possible to write a more "general" class which does all the serialization stuff, where I say serialize xy
bytes and that's it. But what I don't understand is what about "special" toByteArray()
methods like for Strings(UTF-16 encoding)
or Date and Time? If I pack them in a class is that a good solution? Did I gain something with that? Maintable code? High-Performance code??
What would be your approach?
Thx
Решение
May be it's better to create a Map of properties for each class. By default the set is empty but on call e.g. setAddress(address) we call fieldsMap.put(ADDRESS_KEY_STRING,address) instead of assigning to the class' field.
To store all acesses (existing) properties we just go through the fieldsMap storing each Entry.