Replace IsAlive with IsClosed

IsAlive is ambiguous because the connection may be dead and we do not
know it. It implies the possibility of a ping. IsClosed is clearer -- it
does not promise the connection is alive only that it hasn't been
closed.

fixes #2

pgconn.go

@@ -463,10 +463,9 @@ func (pgConn *PgConn) hardClose() error {
 	return pgConn.conn.Close()
 }
 
-// TODO - rethink how to report status. At the moment this is just a temporary measure so pgx.Conn can detect death of
-// underlying connection.
-func (pgConn *PgConn) IsAlive() bool {
-	return pgConn.status >= connStatusIdle
+// IsClosed reports if the connection has been closed.
+func (pgConn *PgConn) IsClosed() bool {
+	return pgConn.status < connStatusIdle
 }
 
 // lock locks the connection. It panics if the connection is already locked or is closed.

pgconn_test.go

@@ -433,7 +433,7 @@ func TestConnExecContextCanceled(t *testing.T) {
 	}
 	err = multiResult.Close()
 	assert.Equal(t, context.DeadlineExceeded, err)
-	assert.False(t, pgConn.IsAlive())
+	assert.True(t, pgConn.IsClosed())
 }
 
 func TestConnExecContextPrecanceled(t *testing.T) {
@@ -566,7 +566,7 @@ func TestConnExecParamsCanceled(t *testing.T) {
 	assert.Equal(t, pgconn.CommandTag(nil), commandTag)
 	assert.Equal(t, context.DeadlineExceeded, err)
 
-	assert.False(t, pgConn.IsAlive())
+	assert.True(t, pgConn.IsClosed())
 }
 
 func TestConnExecParamsPrecanceled(t *testing.T) {
@@ -692,7 +692,7 @@ func TestConnExecPreparedCanceled(t *testing.T) {
 	commandTag, err := result.Close()
 	assert.Equal(t, pgconn.CommandTag(nil), commandTag)
 	assert.Equal(t, context.DeadlineExceeded, err)
-	assert.False(t, pgConn.IsAlive())
+	assert.True(t, pgConn.IsClosed())
 }
 
 func TestConnExecPreparedPrecanceled(t *testing.T) {
@@ -1142,7 +1142,7 @@ func TestConnCopyToCanceled(t *testing.T) {
 	assert.True(t, errors.Is(err, context.DeadlineExceeded))
 	assert.Equal(t, pgconn.CommandTag(nil), res)
 
-	assert.False(t, pgConn.IsAlive())
+	assert.True(t, pgConn.IsClosed())
 }
 
 func TestConnCopyToPrecanceled(t *testing.T) {
@@ -1233,7 +1233,7 @@ func TestConnCopyFromCanceled(t *testing.T) {
 	assert.Equal(t, int64(0), ct.RowsAffected())
 	assert.True(t, errors.Is(err, context.DeadlineExceeded))
 
-	assert.False(t, pgConn.IsAlive())
+	assert.True(t, pgConn.IsClosed())
 }
 
 func TestConnCopyFromPrecanceled(t *testing.T) {