Chapter 4 Flashcards
Are threads async?
Yes. they run at different speeds and can be halted.
Different kind of registers?
Boolean, integer(M-valued)
Degrees of Consistency in registers
Safe, regular, atomic
When is a MRSW safe?
a read() that does not overlap write() returns last value. and if overlap it can return any value within the registers range
When is a MRSW regular?
A read() that does not overlap a write() returns the last value
If a read() overlaps a write() it returns either the old value or the new value
is regular register linearizable?
No
When is a MRSW register atomic?
Each read() returns the last value written
how is MRSW safe boolean register created from SRSW boolean register?
an array of SRSW registers. for read, read seperate own register, but for every write, write to all
difference between safe BooleanMRSW and regular BooleanMRSW.
only if new == old value. Safe can return either Boolean Value. Regular can return old/new, but old == new so can only return x (only write value if distinct)
how does a Regular M-valued MRSW register write and read?
writer: write true to location of X, set lower to false. Reader: read from lower to higher until reads true
What are regular register Conditions:
- No read() call should return a value from the future
- No read() call should return a value from the distant past – only the most recently written non-overlapping value must be returned
What are the Atomic register Conditions:
regular register conditions +
An earlier read() cannot return a value later than that returned by a later read()
(read should be in correct order
Atomic SRSW -> Atomic MRSW
every thread in array, write starts at start, iterates through array. read reads only its own array location
Who has authority at the root of the DNS?
IANA (Internet Assigned Numbers Authority)
By who is IANA operated by?
ICANN (Internet Corporation for Assigned Names and Numbers)
