From 877bf18b7e26a4ee958fa4839c185c87fbcd7560 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Fri, 2 Oct 2020 17:33:20 +1000
Subject: Add retry profiling

---
 tx.go | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

(limited to 'tx.go')

diff --git a/tx.go b/tx.go
index 065cb6c..3a1506c 100644
--- a/tx.go
+++ b/tx.go
@@ -9,15 +9,16 @@ import (
 
 // A Tx represents an atomic transaction.
 type Tx struct {
-	reads     map[*Var]VarValue
-	writes    map[*Var]interface{}
-	watching  map[*Var]struct{}
-	locks     txLocks
-	mu        sync.Mutex
-	cond      sync.Cond
-	waiting   bool
-	completed bool
-	tries     int
+	reads          map[*Var]VarValue
+	writes         map[*Var]interface{}
+	watching       map[*Var]struct{}
+	locks          txLocks
+	mu             sync.Mutex
+	cond           sync.Cond
+	waiting        bool
+	completed      bool
+	tries          int
+	numRetryValues int
 }
 
 // Check that none of the logged values have changed since the transaction began.
@@ -97,9 +98,18 @@ func (tx *Tx) Set(v *Var, val interface{}) {
 	tx.writes[v] = val
 }
 
-// Retry aborts the transaction and retries it when a Var changes.
-func (tx *Tx) Retry() {
-	panic(Retry)
+type txProfileValue struct {
+	*Tx
+	int
+}
+
+// Retry aborts the transaction and retries it when a Var changes. You can return from this method
+// to satisfy return values, but it should never actually return anything as it panics internally.
+func (tx *Tx) Retry() interface{} {
+	retries.Add(txProfileValue{tx, tx.numRetryValues}, 0)
+	tx.numRetryValues++
+	panic(retry)
+	panic("unreachable")
 }
 
 // Assert is a helper function that retries a transaction if the condition is
@@ -117,9 +127,17 @@ func (tx *Tx) reset() {
 	for k := range tx.writes {
 		delete(tx.writes, k)
 	}
+	tx.removeRetryProfiles()
 	tx.resetLocks()
 }
 
+func (tx *Tx) removeRetryProfiles() {
+	for tx.numRetryValues > 0 {
+		tx.numRetryValues--
+		retries.Remove(txProfileValue{tx, tx.numRetryValues})
+	}
+}
+
 func (tx *Tx) recycle() {
 	for v := range tx.watching {
 		delete(tx.watching, v)
-- 
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