block.py

This is an example of record locking and unlocking written in Python.

import sys
import struct
import math
import os
import platform
 
if (platform.system() == "Windows"):
    sys.path.append("C:\\Program Files\\Actian\\Zen\\bin")
else:
    sys.path.append("/usr/local/actianzen/lib64")
 
import btrievePython
 
def updateRecord(expectRecordInUse):
    btrieveClient = btrievePython.BtrieveClient(0,2)
    assert(btrieveClient != None)
 
    btrieveFile = btrievePython.BtrieveFile()
    assert(btrieveFile != None)
 
    rc = btrieveClient.FileOpen(btrieveFile, btrieveFileName, None, btrievePython.Btrieve.OPEN_MODE_NORMAL)
    assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileOpen():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
    record = struct.pack(recordFormat, 0, 0, 0)
 
    rc = btrieveFile.RecordRetrieveFirst(btrievePython.Btrieve.INDEX_1, record)
    assert(rc == recordLength), "Error: BtrieveFile::RecordRetrieveFirst():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(btrieveFile.GetLastStatusCode()))
 
    i, isqr, isqrt = struct.unpack(recordFormat, record)
    isqr += 1
    isqrt += 1
    record = struct.pack(recordFormat, i, isqr, isqrt)
 
 
    rc = btrieveFile.RecordUpdate(record)
 
 
    if (expectRecordInUse == True):
        assert(rc == btrievePython.Btrieve.STATUS_CODE_RECORD_INUSE), "Error: BtrieveFile::RecordUpdate():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
    elif (expectRecordInUse == False):
        assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveFile::RecordUpdate():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
    rc = btrieveClient.FileClose(btrieveFile)
    assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileClose():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
    return rc
 
min_x = 0
max_x = 255
btrieveFileName = "squaresAndSquareRoots.btr"
recordFormat = "<BHd"
recordLength = 11
keyFormat = "<B"
 
# If the incorrect number of arguments were given.
if (len(sys.argv) != 1):
    sys.exit("Usage: " + os.path.basename(sys.argv[0]))
 
btrieveClient = btrievePython.BtrieveClient(0,1)
assert(btrieveClient != None)
 
btrieveFileAttributes = btrievePython.BtrieveFileAttributes()
assert(btrieveFileAttributes != None)
 
rc = btrieveFileAttributes.SetFixedRecordLength(recordLength)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveFileAttributes::SetFixedRecordLength():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
rc = btrieveClient.FileCreate(btrieveFileAttributes, btrieveFileName, btrievePython.Btrieve.CREATE_MODE_OVERWRITE)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileCreate():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
btrieveFile = btrievePython.BtrieveFile()
assert(btrieveFile != None)
 
rc = btrieveClient.FileOpen(btrieveFile, btrieveFileName, None, btrievePython.Btrieve.OPEN_MODE_NORMAL)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileOpen():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
# For all the values of x.
for i in range(min_x, max_x + 1):
    record = struct.pack(recordFormat, i, i * i, math.sqrt(i))
 
    rc = btrieveFile.RecordCreate(record)
    assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveFile::RecordCreate():%d:%s.\n"  % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
btrieveKeySegment = btrievePython.BtrieveKeySegment()
assert(btrieveKeySegment != None)
 
rc = btrieveKeySegment.SetField(0, 1, btrievePython.Btrieve.DATA_TYPE_UNSIGNED_BINARY)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveKeySegment::SetField():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
btrieveIndexAttributes = btrievePython.BtrieveIndexAttributes()
assert(btrieveIndexAttributes != None)
 
rc = btrieveIndexAttributes.AddKeySegment(btrieveKeySegment)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveIndexAttributes::AddKeySegment():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
rc = btrieveFile.IndexCreate(btrieveIndexAttributes)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveFile::IndexCreate():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
# print record
record = struct.pack(recordFormat, 0, 0, 0)
 
 
rc = btrieveFile.RecordRetrieveFirst(btrievePython.Btrieve.INDEX_1, record, btrievePython.Btrieve.LOCK_MODE_SINGLE_WAIT)
assert(rc == recordLength), "Error: BtrieveFile::RecordRetrieveFirst():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(btrieveFile.GetLastStatusCode()))
 
 
print ("record before update:", struct.unpack(recordFormat, record))
 
rc = updateRecord(True)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR)
 
 
rc = btrieveFile.RecordUnlock(btrievePython.Btrieve.UNLOCK_MODE_SINGLE)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveFile::RecordUnlock():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
 
rc = btrieveFile.RecordRetrieveFirst(btrievePython.Btrieve.INDEX_1, record)
assert(rc == recordLength), "Error: BtrieveFile::RecordRetrieveFirst():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(btrieveFile.GetLastStatusCode()))
 
print ("record after update while locked:", struct.unpack(recordFormat, record))
 
rc = updateRecord(False)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR)
 
rc = btrieveFile.RecordRetrieveFirst(btrievePython.Btrieve.INDEX_1, record, btrievePython.Btrieve.LOCK_MODE_SINGLE_WAIT)
assert(rc == recordLength), "Error: BtrieveFile::RecordRetrieveFirst():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(btrieveFile.GetLastStatusCode()))
 
print ("record after update while unlocked:", struct.unpack(recordFormat, record))
 
rc = btrieveClient.FileClose(btrieveFile)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileClose():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))
 
rc = btrieveClient.FileDelete(btrieveFileName)
assert(rc == btrievePython.Btrieve.STATUS_CODE_NO_ERROR), "Error: BtrieveClient::FileDelete():%d:%s.\n" % (rc, btrievePython.Btrieve_StatusCodeToString(rc))