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Marco Realacci 2025-04-04 23:39:27 +02:00
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6
Concurrent Systems/notes/7- MUTEX-free concurrency.md
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@ -64,7 +64,7 @@ this implementation satisfies the three requirements for the splitter
- let us consider the last process that writes into LAST (this is an atomic register, so this is meaningful)
- if the door is closed, it receives R and √
3. let $p_i$ be the first process that receives $S \to LAST=i$ in its second if
![[images/Pasted image 20250324091452.png]]
![[/Concurrent Systems/notes/images/Pasted image 20250324091452.png]]
### An Obstruction-free Timestamp Generator
A **timestamp generator** is a concurrent object that provides a single operation get_ts such that:
@ -98,7 +98,7 @@ this implementation satisfies the three properties of the timestamp generator
- every process that starts after its termination will find NEXT to a greater value (NEXT never decreases!)
3. Obstruction freedom is trivial
**REMARK:** this implementation doesn’t satisfy the non-blocking property:![[images/Pasted image 20250324092633.png]]
**REMARK:** this implementation doesn’t satisfy the non-blocking property:![[/Concurrent Systems/notes/images/Pasted image 20250324092633.png]]
### A Wait-free Stack
REG is an unbounded array of atomic registers (the stack)
@ -149,7 +149,7 @@ This is needed for the so called ABA problem with compare&set:
- with the compare&set you mainly test that the sequence_number has not changed
TOP : a register that can be read or compare&setted
![[images/Pasted image 20250324100652.png]]
![[/Concurrent Systems/notes/images/Pasted image 20250324100652.png]]
```
push(w) :=