[foreign-memaccess] RFR 8234581: Cleanup use of exceptions in the memory access API

[Maurizio Cimadamore]

Chris has observed (offline) that in the JDK we typically do not add 
unchecked exceptions to the 'throws' clause (but only add @throws 
taglets to the javadoc).

I will do a pass and remove them.

Maurizio

On 21/11/2019 13:28, Maurizio Cimadamore wrote:
>
> On 21/11/2019 13:07, sundararajan.athijegannathan at oracle.com wrote:
>> Looks good.
>>
>> Minor:
>>
>> +
>>
>> private static boolean skipZeroMemory;
>> +
>> +static {
>> +skipZeroMemory = 
>> GetBooleanAction.privilegedGetProperty(“jdk.internal.foreign.skipZeroMemory”);
>> +}
>>
>>
>> could be static final & inline initialization.
>
> Whoops - good catch; will fix before push
>
> Maurizio
>
>>
>> -Sundar
>>
>> On 21/11/19 6:23 pm, Maurizio Cimadamore wrote:
>>> New day, new cleanup :-)
>>>
>>> This time, following some of the indications from Paul, the goal is 
>>> to cleanup usages of exceptions in the memory access API. I found 4 
>>> broad categories of issues:
>>>
>>> - We sometimes throw IAE where an IOOB would be preferred (namely, 
>>> MemorySegment::slice and MemoryAddress::copy)
>>>
>>> - We sometimes use RuntimeException to document unforeseen failures 
>>> of Unsafe::allocateMemory (ByteBuffer::allocateDirect does not do so)
>>>
>>> - The handling of exceptions when forming layout paths is plain 
>>> inconsistent - and IAE should be used throughout
>>>
>>> - MemorySegment::close should always throw ISE if the state is not 
>>> valid
>>>
>>>
>>> The changes in LayoutPath handling required some deeper changes in 
>>> the implementation - which now triggers an uniform IAE with a 
>>> message of the kind: Bad layout path: <cause>.
>>>
>>>
>>> Since I was there, I also added the logic to zero the native memory 
>>> allocated with MemorySegment::allocateNative. This behavior can be 
>>> disabled with a runtime flag: -Djdk.internal.foreign.skipZeroMemory.
>>>
>>>
>>> I also made extra sure that the exceptions thrown in the code are 
>>> reflected in the throws clause of the API methods, and that there 
>>> are the right @throw taglets for them.
>>>
>>> Webrev:
>>>
>>> http://cr.openjdk.java.net/~mcimadamore/panama/8234581/
>>>
>>> javadoc:
>>>
>>> cr.openjdk.java.net/~mcimadamore/panama/8234581_javadoc
>>>
>>>
>>> Cheers
>>> Maurizio
>>>