Commit 5c27499c authored by Zhen Zhang's avatar Zhen Zhang Committed by Robbert Krebbers

Define acquire of spin lock in terms of try_acquire.

parent a4ee4c0d
Pipeline #2755 passed with stage
in 9 minutes and 29 seconds
...@@ -6,11 +6,11 @@ From iris.algebra Require Import excl. ...@@ -6,11 +6,11 @@ From iris.algebra Require Import excl.
From iris.heap_lang.lib Require Import lock. From iris.heap_lang.lib Require Import lock.
Definition newlock : val := λ: <>, ref #false. Definition newlock : val := λ: <>, ref #false.
Definition try_acquire : val := λ: "l", CAS "l" #false #true.
Definition acquire : val := Definition acquire : val :=
rec: "acquire" "l" := rec: "acquire" "l" := if: try_acquire "l" then #() else "acquire" "l".
if: CAS "l" #false #true then #() else "acquire" "l".
Definition release : val := λ: "l", "l" <- #false. Definition release : val := λ: "l", "l" <- #false.
Global Opaque newlock acquire release. Global Opaque newlock try_acquire acquire release.
(** The CMRA we need. *) (** The CMRA we need. *)
(* Not bundling heapG, as it may be shared with other users. *) (* Not bundling heapG, as it may be shared with other users. *)
...@@ -57,17 +57,26 @@ Section proof. ...@@ -57,17 +57,26 @@ Section proof.
iVsIntro. iApply "HΦ". iExists l. eauto. iVsIntro. iApply "HΦ". iExists l. eauto.
Qed. Qed.
Lemma acquire_spec γ lk R (Φ : val iProp Σ) : Lemma try_acquire_spec γ lk R (Φ: val iProp Σ) :
is_lock γ lk R (locked γ - R - Φ #()) WP acquire lk {{ Φ }}. is_lock γ lk R ((locked γ - R - Φ #true) Φ #false)
WP try_acquire lk {{ Φ }}.
Proof. Proof.
iIntros "[Hl HΦ]". iDestruct "Hl" as (l) "(% & #? & % & #?)". subst. iIntros "[#Hl HΦ]". iDestruct "Hl" as (l) "(% & #? & % & #?)". subst.
iLöb as "IH". wp_rec. wp_bind (CAS _ _ _)%E. wp_rec. iInv N as ([]) "[Hl HR]" "Hclose".
iInv N as ([]) "[Hl HR]" "Hclose".
- wp_cas_fail. iVs ("Hclose" with "[Hl]"); first (iNext; iExists true; eauto). - wp_cas_fail. iVs ("Hclose" with "[Hl]"); first (iNext; iExists true; eauto).
iVsIntro. wp_if. by iApply "IH". iVsIntro. iDestruct "HΦ" as "[_ HΦ]". iApply "HΦ".
- wp_cas_suc. iDestruct "HR" as "[Hγ HR]". - wp_cas_suc. iDestruct "HR" as "[Hγ HR]".
iVs ("Hclose" with "[Hl]"); first (iNext; iExists true; eauto). iVs ("Hclose" with "[Hl]"); first (iNext; iExists true; eauto).
iVsIntro. wp_if. iApply ("HΦ" with "[-HR] HR"). by iFrame. iVsIntro. iDestruct "HΦ" as "[HΦ _]". rewrite /locked. by iApply ("HΦ" with "Hγ HR").
Qed.
Lemma acquire_spec γ lk R (Φ : val iProp Σ) :
is_lock γ lk R (locked γ - R - Φ #()) WP acquire lk {{ Φ }}.
Proof.
iIntros "[#Hl HΦ]". iLöb as "IH". wp_rec. wp_bind (try_acquire _).
iApply try_acquire_spec. iFrame "#". iSplit.
- iIntros "Hlked HR". wp_if. iVsIntro. iApply ("HΦ" with "Hlked HR").
- wp_if. iApply ("IH" with "HΦ").
Qed. Qed.
Lemma release_spec γ lk R (Φ : val iProp Σ) : Lemma release_spec γ lk R (Φ : val iProp Σ) :
......
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