SQUASH Use MAX_TID as stand-in for "no known First TID"

This simplifies the code a lot.

neo/master/handlers/administration.py

@@ -239,8 +239,7 @@ class AdministrationHandler(MasterHandler):
         app = self.app
         if app.getLastTransaction() <= tid:
             raise AnswerDenied("Truncating after last transaction does nothing")
-        first_tid = app.tm.getFirstTID()
-        if first_tid is None or first_tid > tid:
+        if app.tm.getFirstTID() > tid:
             raise AnswerDenied("Truncating before first transaction is "
                                "probably not what you intended to do")
         if app.pm.getApprovedRejected(add64(tid, 1))[0]:

neo/master/transactions.py

@@ -20,7 +20,7 @@ from struct import pack, unpack
 from neo.lib import logging
 from neo.lib.exception import ProtocolError
 from neo.lib.handler import DelayEvent, EventQueue
-from neo.lib.protocol import uuid_str, ZERO_OID, ZERO_TID
+from neo.lib.protocol import uuid_str, ZERO_OID, ZERO_TID, MAX_TID
 from neo.lib.util import dump, u64, addTID, tidFromTime
 
 class Transaction(object):
@@ -179,7 +179,7 @@ class TransactionManager(EventQueue):
         self._ttid_dict = {}
         self._last_oid = ZERO_OID
         self._last_tid = ZERO_TID
-        self._first_tid = None
+        self._first_tid = MAX_TID
         self._unlockPending = self._firstUnlockPending
         # queue filled with ttids pointing to transactions with increasing tids
         self._queue = deque()
@@ -215,8 +215,7 @@ class TransactionManager(EventQueue):
         return oid_list
 
     def setFirstTID(self, tid):
-        first_tid = self._first_tid
-        if tid is not None and (first_tid is None or first_tid > tid):
+        if self._first_tid > tid:
             self._first_tid = tid
 
     def getFirstTID(self):

neo/storage/database/manager.py

@@ -770,14 +770,8 @@ class DatabaseManager(object):
         """
         x = self._readable_set
         if x:
-            getFirstTID = self._getFirstTID
-            min_tid = None
-            for partition in x:
-                tid = getFirstTID(partition)
-                if tid is not None and (min_tid is None or tid < min_tid):
-                    min_tid = tid
-            if min_tid is not None:
-                return util.p64(min_tid)
+            return util.p64(min(map(self._getFirstTID, x)))
+        return MAX_TID
 
     def _getLastTID(self, partition, max_tid=None):
         """Return tid of last transaction <= 'max_tid' in given 'partition'

neo/storage/database/mysql.py

@@ -53,7 +53,7 @@ from .manager import MVCCDatabaseManager, splitOIDField
 from neo.lib import logging, util
 from neo.lib.exception import NonReadableCell, UndoPackError
 from neo.lib.interfaces import implements
-from neo.lib.protocol import CellStates, ZERO_OID, ZERO_TID, ZERO_HASH
+from neo.lib.protocol import CellStates, ZERO_OID, ZERO_TID, ZERO_HASH, MAX_TID
 
 
 class MysqlError(DatabaseFailure):
@@ -464,6 +464,7 @@ class MySQLDatabaseManager(MVCCDatabaseManager):
         if tid_list:
             (tid, ), = tid_list
             return tid
+        return util.u64(MAX_TID)
 
     def _getLastTID(self, partition, max_tid=None):
         x = "WHERE `partition`=%s" % partition

neo/storage/database/sqlite.py

@@ -28,7 +28,7 @@ from .manager import DatabaseManager, splitOIDField
 from neo.lib import logging, util
 from neo.lib.exception import NonReadableCell, UndoPackError
 from neo.lib.interfaces import implements
-from neo.lib.protocol import CellStates, ZERO_OID, ZERO_TID, ZERO_HASH
+from neo.lib.protocol import CellStates, ZERO_OID, ZERO_TID, ZERO_HASH, MAX_TID
 
 def unique_constraint_message(table, *columns):
     c = sqlite3.connect(":memory:")
@@ -344,11 +344,11 @@ class SQLiteDatabaseManager(DatabaseManager):
         return self.query("SELECT * FROM pt")
 
     def _getFirstTID(self, partition):
-        try:
-            return self.query("SELECT MIN(tid) FROM trans WHERE partition=?",
+        tid = self.query("SELECT MIN(tid) FROM trans WHERE partition=?",
                          (partition,)).fetchone()[0]
-        except TypeError:
-            pass
+        if tid is None:
+            return util.u64(MAX_TID)
+        return tid
 
     def _getLastTID(self, partition, max_tid=None):
         x = self.query

neo/tests/protocol

@@ -13,7 +13,7 @@ AnswerFetchObjects(?p64,?p64,{:})
 AnswerFetchTransactions(?p64,[],?p64)
 AnswerFinalTID(p64)
 AnswerInformationLocked(p64)
-AnswerLastIDs(?p64,?p64,?p64)
+AnswerLastIDs(?p64,?p64,p64)
 AnswerLastTransaction(p64)
 AnswerLockedTransactions({p64:?p64})
 AnswerMonitorInformation([?bin],[?bin],bin)

neo/tests/storage/testStorageDBTests.py

@@ -183,7 +183,7 @@ class StorageDBTests(NeoUnitTestBase):
         txn1, objs1 = self.getTransaction([oid1])
         txn2, objs2 = self.getTransaction([oid2])
         # nothing in database
-        self.assertEqual(self.db.getFirstTID(), None)
+        self.assertEqual(self.db.getFirstTID(), MAX_TID)
         self.assertEqual(self.db.getLastIDs(), (None, None))
         self.assertEqual(self.db.getUnfinishedTIDDict(), {})
         self.assertEqual(self.db.getObject(oid1), None)