public async Task <GdidBlock> AllocateBlockAsync(string scopeName, string sequenceName, int blockSize, ulong?vicinity = 1152921504606846975)
{
var result = await ComponentDirector.CallServiceAsync(ESConsts.SVC_PATH_GDID, ++m_Shard,
async (client) =>
{
var json = await client.PostAndGetJsonMapAsync("", new { scopeName, sequenceName, blockSize, vicinity });
var block = new GdidBlock();
JsonReader.ToDoc(block, json);
return(block);
}
);
return(result);
}
private GdidBlock allocate(byte authority, string scopeName, string sequenceName, int blockSize, ulong?vicinity)
{
var scopeKey = "{0}://{1}".Args(AuthorityPathSeg(authority), scopeName);
var scope = m_Scopes.GetOrRegister(scopeKey, (key) => new scope {
Name = key
}, scopeKey);
var sequence = scope.Sequences.GetOrRegister(sequenceName, (_) => new sequence {
Name = sequenceName, New = true
}, 0); //with NEW=TRUE
var result = new GdidBlock()
{
ScopeName = scopeName,
SequenceName = sequenceName,
Authority = authority,
AuthorityHost = App.GetThisHostName(),
BlockSize = blockSize,
ServerUTCTime = App.TimeSource.UTCNow
};
lock (scope)
{
//0. If just allocated then need to read from disk
if (sequence.New)
{
sequence.New = false;
var id = ReadFromLocations(authority, scopeName, sequenceName);
sequence.Era = id.Era;
sequence.Value = id.Value;
}
//1. make a local copy of vars, that may mutate but don't get committed until written to disk
var era = sequence.Era;
var value = sequence.Value;
//1.1 make sure that GDID.Zero is never returned
if (authority == 0 && era == 0 && value == 0)
{
value = 1; //Don't start value from Zero in ERA=0 and Authority=0
}
if (value >= GDID.COUNTER_MAX - (ulong)(blockSize + 1)) //its time to update ERA (+1 for safeguard/edge case)
{
if (era == uint.MaxValue - 4) //ALERT, with some room
{
WriteLog(MessageType.CriticalAlert, "allocate()", StringConsts.GDIDAUTH_ERA_EXHAUSTED_ALERT.Args(scopeName, sequenceName));
}
if (era == uint.MaxValue) //hard stop
{
var txt = StringConsts.GDIDAUTH_ERA_EXHAUSTED_ERROR.Args(scopeName, sequenceName);
WriteLog(MessageType.CatastrophicError, "allocate()", txt);
throw new GdidException(txt);
}
era++;
value = 0;
Instrumentation.AuthEraPromotedEvent.Happened(App.Instrumentation, scopeName, sequenceName);
WriteLog(MessageType.Warning, "allocate()", StringConsts.GDIDAUTH_ERA_PROMOTED_WARNING.Args(scopeName, sequenceName, era));
}
result.Era = era;
result.StartCounterInclusive = value;
value = value + (ulong)blockSize;
//2. Try to write to disk, if it fails we could not allocate anything and will bail out with exception
WriteToLocations(authority, scopeName, sequenceName, new _id(era, value));
//3. only after write to disk succeeds do we commit the changes back into the sequence instance
sequence.Era = era;
sequence.Value = value;
}
return(result);
}
