mon: generalize memory accounting

Our use of MemoryMonitor had previously been limited solely to tracking
memory allocations. However, future changes will use this mechanism
to track disk usage. Therefore, Memory{Monitor, Account} have been
renamed to Resource{Monitor, Account} and memory specific comments and
code have been generalized.

server.go

@@ -106,8 +106,8 @@ type Server struct {
 		draining      bool
 	}
 
-	sqlMemoryPool mon.MemoryMonitor
-	connMonitor   mon.MemoryMonitor
+	sqlMemoryPool mon.BytesMonitor
+	connMonitor   mon.BytesMonitor
 }
 
 // ServerMetrics is the set of metrics for the pgwire server.
@@ -150,7 +150,7 @@ func MakeServer(
 	cfg *base.Config,
 	executor *sql.Executor,
 	internalMemMetrics *sql.MemoryMetrics,
-	parentMemoryMonitor *mon.MemoryMonitor,
+	parentMemoryMonitor *mon.BytesMonitor,
 	histogramWindow time.Duration,
 ) *Server {
 	server := &Server{
@@ -160,12 +160,14 @@ func MakeServer(
 		metrics:    makeServerMetrics(internalMemMetrics, histogramWindow),
 	}
 	server.sqlMemoryPool = mon.MakeMonitor("sql",
+		mon.MemoryResource,
 		server.metrics.SQLMemMetrics.CurBytesCount,
 		server.metrics.SQLMemMetrics.MaxBytesHist,
 		0, noteworthySQLMemoryUsageBytes)
 	server.sqlMemoryPool.Start(context.Background(), parentMemoryMonitor, mon.BoundAccount{})
 
 	server.connMonitor = mon.MakeMonitor("conn",
+		mon.MemoryResource,
 		server.metrics.ConnMemMetrics.CurBytesCount,
 		server.metrics.ConnMemMetrics.MaxBytesHist,
 		int64(connReservationBatchSize)*baseSQLMemoryBudget, noteworthyConnMemoryUsageBytes)

v3.go

@@ -186,11 +186,11 @@ type v3Conn struct {
 
 	metrics *ServerMetrics
 
-	sqlMemoryPool *mon.MemoryMonitor
+	sqlMemoryPool *mon.BytesMonitor
 }
 
 func makeV3Conn(
-	conn net.Conn, metrics *ServerMetrics, sqlMemoryPool *mon.MemoryMonitor, executor *sql.Executor,
+	conn net.Conn, metrics *ServerMetrics, sqlMemoryPool *mon.BytesMonitor, executor *sql.Executor,
 ) v3Conn {
 	return v3Conn{
 		conn:          conn,

v3_test.go

@@ -35,7 +35,9 @@ import (
 
 func makeTestV3Conn(c net.Conn) v3Conn {
 	metrics := makeServerMetrics(nil, metric.TestSampleInterval)
-	mon := mon.MakeUnlimitedMonitor(context.Background(), "test", nil, nil, 1000)
+	mon := mon.MakeUnlimitedMonitor(
+		context.Background(), "test", mon.MemoryResource, nil, nil, 1000,
+	)
 	exec := sql.NewExecutor(
 		sql.ExecutorConfig{
 			AmbientCtx:              log.AmbientContext{Tracer: tracing.NewTracer()},