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Remove empty keys #825

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merged 8 commits into from
Jun 15, 2019
Merged

Remove empty keys #825

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bfc3ae0
Close https://github.com/neo-project/neo/issues/824
shargon Jun 13, 2019
cef97ed
Merge branch 'master' into delete-on-empty
shargon Jun 13, 2019
cac2cb1
optimize
erikzhang Jun 13, 2019
b3d197b
remove redundancy
igormcoelho Jun 13, 2019
a3abddd
simplified
igormcoelho Jun 13, 2019
815fcb4
allow const empty array
igormcoelho Jun 13, 2019
b41742a
Update InteropService.cs
shargon Jun 13, 2019
babdc1d
Update InteropService.cs
erikzhang Jun 15, 2019
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24 changes: 19 additions & 5 deletions neo/SmartContract/InteropService.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -546,16 +546,30 @@ private static bool PutEx(ApplicationEngine engine, StorageContext context, byte
if (value.Length > MaxStorageValueSize) return false;
if (context.IsReadOnly) return false;
if (!CheckStorageContext(engine, context)) return false;

StorageKey skey = new StorageKey
{
ScriptHash = context.ScriptHash,
Key = key
};
StorageItem item = engine.Snapshot.Storages.GetAndChange(skey, () => new StorageItem());
if (item.IsConstant) return false;
item.Value = value;
item.IsConstant = flags.HasFlag(StorageFlags.Constant);
return true;

StorageItem item = engine.Snapshot.Storages.TryGet(skey);
if (item?.IsConstant == true) return false;

if (value.Length == 0)
{
// If is empty, we try to remove it

engine.Snapshot.Storages.Delete(skey);
return true;
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If I put an empty bytes with StorageFlags.Constant flag, what will happen?

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The expected behaviour is: write nothing, read empty bytes

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@igormcoelho igormcoelho Jun 13, 2019 •
edited
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What's an example use case for const? I think you're right... logically speaking, if someone wants to keep a constant value, that value could be zero. So we need to keep it allow it to be unchanged in the future. We cannot pre-reap const empty values @shargon, because it may be part of contract logic, and perhaps be re-written in the future because we accidentally pre-dropped its "constness".

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@igormcoelho igormcoelho Jun 13, 2019 •
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Only explicit Delete will destroy them, right @erikzhang ? I just noticed Delete cannot reap const values too. So these are contract-lifetime values, correct? Only Contract.Destroy or Migrate can reap them.

}
else
{
item = engine.Snapshot.Storages.GetAndChange(skey, () => new StorageItem());
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item.Value = value;
item.IsConstant = flags.HasFlag(StorageFlags.Constant);
return true;
}
}

private static bool Storage_Put(ApplicationEngine engine)
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