1 files changed, 0 insertions, 174 deletions
diff --git a/cmd/santa-example/main.go b/cmd/santa-example/main.go
deleted file mode 100644
index 76c0fbc..0000000
--- a/cmd/santa-example/main.go
+++ /dev/null
@@ -1,174 +0,0 @@
-// An implementation of the "Santa Claus problem" as defined in 'Beautiful
-// concurrency', found here: http://research.microsoft.com/en-us/um/people/simonpj/papers/stm/beautiful.pdf
-//
-// The problem is given as:
-//
-//	Santa repeatedly sleeps until wakened by either all of his nine reindeer,
-//	back from their holidays, or by a group of three of his ten elves. If
-//	awakened by the reindeer, he harnesses each of them to his sleigh,
-//	delivers toys with them and finally unharnesses them (allowing them to
-//	go off on holiday). If awakened by a group of elves, he shows each of the
-//	group into his study, consults with them on toy R&D and finally shows
-//	them each out (allowing them to go back to work). Santa should give
-//	priority to the reindeer in the case that there is both a group of elves
-//	and a group of reindeer waiting.
-//
-// Here we follow the solution given in the paper, described as such:
-//
-//	Santa makes one "Group" for the elves and one for the reindeer. Each elf
-//	(or reindeer) tries to join its Group. If it succeeds, it gets two
-//	"Gates" in return. The first Gate allows Santa to control when the elf
-//	can enter the study, and also lets Santa know when they are all inside.
-//	Similarly, the second Gate controls the elves leaving the study. Santa,
-//	for his part, waits for either of his two Groups to be ready, and then
-//	uses that Group's Gates to marshal his helpers (elves or reindeer)
-//	through their task. Thus the helpers spend their lives in an infinite
-//	loop: try to join a group, move through the gates under Santa's control,
-//	and then delay for a random interval before trying to join a group again.
-//
-// See the paper for more details regarding the solution's implementation.
-package main
-
-import (
-	"fmt"
-	"math/rand"
-	"time"
-
-	"github.com/anacrolix/stm"
-)
-
-type gate struct {
-	capacity  int
-	remaining *stm.Var[int]
-}
-
-func (g gate) pass() {
-	stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
-		rem := g.remaining.Get(tx)
-		// wait until gate can hold us
-		tx.Assert(rem > 0)
-		g.remaining.Set(tx, rem-1)
-	}))
-}
-
-func (g gate) operate() {
-	// open gate, reseting capacity
-	stm.AtomicSet(g.remaining, g.capacity)
-	// wait for gate to be full
-	stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
-		rem := g.remaining.Get(tx)
-		tx.Assert(rem == 0)
-	}))
-}
-
-func newGate(capacity int) gate {
-	return gate{
-		capacity:  capacity,
-		remaining: stm.NewVar(0), // gate starts out closed
-	}
-}
-
-type group struct {
-	capacity     int
-	remaining    *stm.Var[int]
-	gate1, gate2 *stm.Var[gate]
-}
-
-func newGroup(capacity int) *group {
-	return &group{
-		capacity:  capacity,
-		remaining: stm.NewVar(capacity), // group starts out with full capacity
-		gate1:     stm.NewVar(newGate(capacity)),
-		gate2:     stm.NewVar(newGate(capacity)),
-	}
-}
-
-func (g *group) join() (g1, g2 gate) {
-	stm.Atomically(stm.VoidOperation(func(tx *stm.Tx) {
-		rem := g.remaining.Get(tx)
-		// wait until the group can hold us
-		tx.Assert(rem > 0)
-		g.remaining.Set(tx, rem-1)
-		// return the group's gates
-		g1 = g.gate1.Get(tx)
-		g2 = g.gate2.Get(tx)
-	}))
-	return
-}
-
-func (g *group) await(tx *stm.Tx) (gate, gate) {
-	// wait for group to be empty
-	rem := g.remaining.Get(tx)
-	tx.Assert(rem == 0)
-	// get the group's gates
-	g1 := g.gate1.Get(tx)
-	g2 := g.gate2.Get(tx)
-	// reset group
-	g.remaining.Set(tx, g.capacity)
-	g.gate1.Set(tx, newGate(g.capacity))
-	g.gate2.Set(tx, newGate(g.capacity))
-	return g1, g2
-}
-
-func spawnElf(g *group, id int) {
-	for {
-		in, out := g.join()
-		in.pass()
-		fmt.Printf("Elf %v meeting in the study\n", id)
-		out.pass()
-		// sleep for a random interval <5s
-		time.Sleep(time.Duration(rand.Intn(5000)) * time.Millisecond)
-	}
-}
-
-func spawnReindeer(g *group, id int) {
-	for {
-		in, out := g.join()
-		in.pass()
-		fmt.Printf("Reindeer %v delivering toys\n", id)
-		out.pass()
-		// sleep for a random interval <5s
-		time.Sleep(time.Duration(rand.Intn(5000)) * time.Millisecond)
-	}
-}
-
-type selection struct {
-	task         string
-	gate1, gate2 gate
-}
-
-func chooseGroup(g *group, task string, s *selection) stm.Operation[struct{}] {
-	return stm.VoidOperation(func(tx *stm.Tx) {
-		s.gate1, s.gate2 = g.await(tx)
-		s.task = task
-	})
-}
-
-func spawnSanta(elves, reindeer *group) {
-	for {
-		fmt.Println("-------------")
-		var s selection
-		stm.Atomically(stm.Select(
-			// prefer reindeer to elves
-			chooseGroup(reindeer, "deliver toys", &s),
-			chooseGroup(elves, "meet in my study", &s),
-		))
-		fmt.Printf("Ho! Ho! Ho! Let's %s!\n", s.task)
-		s.gate1.operate()
-		// helpers do their work here...
-		s.gate2.operate()
-	}
-}
-
-func main() {
-	elfGroup := newGroup(3)
-	for i := 0; i < 10; i++ {
-		go spawnElf(elfGroup, i)
-	}
-	reinGroup := newGroup(9)
-	for i := 0; i < 9; i++ {
-		go spawnReindeer(reinGroup, i)
-	}
-	// blocks forever
-	spawnSanta(elfGroup, reinGroup)
-}