Fix panic: runtime error: index out of range

There was a fix in 5b1791, but is not present in the current branch likely due to a rebase issue.
The current code panics with a query like:

select value from cpu group by host order by time desc limit 1

This fixes the panic as well as prevents #5193 from re-occurring.  The issue is that agressively
closing the cursors clears out the seeks slice so re-seeking will fail.

cmd/influxd/run/server.go

@@ -30,7 +30,7 @@ import (
 	"github.com/influxdata/influxdb/services/udp"
 	"github.com/influxdata/influxdb/tcp"
 	"github.com/influxdata/influxdb/tsdb"
-	client "github.com/influxdb/usage-client/v1"
+	client "github.com/influxdata/usage-client/v1"
 	// Initialize the engine packages
 	_ "github.com/influxdata/influxdb/tsdb/engine"
 )

tsdb/engine/tsm1/iterator.gen.go

@@ -1,5 +1,8 @@
 // Generated by tmpl
 // https://github.com/benbjohnson/tmpl
+//
+// DO NOT EDIT!
+// Source: iterator.gen.go.tmpl
 
 package tsm1
 
@@ -240,7 +243,6 @@ func (c *floatAscendingCursor) peekCache() (t int64, v float64) {
 // peekTSM returns the current time/value from tsm.
 func (c *floatAscendingCursor) peekTSM() (t int64, v float64) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, math.NaN()
 	}
 
@@ -294,7 +296,6 @@ func (c *floatAscendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadFloatBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -352,7 +353,6 @@ func (c *floatDescendingCursor) peekCache() (t int64, v float64) {
 // peekTSM returns the current time/value from tsm.
 func (c *floatDescendingCursor) peekTSM() (t int64, v float64) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, math.NaN()
 	}
 
@@ -406,7 +406,6 @@ func (c *floatDescendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadFloatBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -576,7 +575,6 @@ func (c *integerAscendingCursor) peekCache() (t int64, v int64) {
 // peekTSM returns the current time/value from tsm.
 func (c *integerAscendingCursor) peekTSM() (t int64, v int64) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, 0
 	}
 
@@ -630,7 +628,6 @@ func (c *integerAscendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadIntegerBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -688,7 +685,6 @@ func (c *integerDescendingCursor) peekCache() (t int64, v int64) {
 // peekTSM returns the current time/value from tsm.
 func (c *integerDescendingCursor) peekTSM() (t int64, v int64) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, 0
 	}
 
@@ -742,7 +738,6 @@ func (c *integerDescendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadIntegerBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -912,7 +907,6 @@ func (c *stringAscendingCursor) peekCache() (t int64, v string) {
 // peekTSM returns the current time/value from tsm.
 func (c *stringAscendingCursor) peekTSM() (t int64, v string) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, ""
 	}
 
@@ -966,7 +960,6 @@ func (c *stringAscendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadStringBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -1024,7 +1017,6 @@ func (c *stringDescendingCursor) peekCache() (t int64, v string) {
 // peekTSM returns the current time/value from tsm.
 func (c *stringDescendingCursor) peekTSM() (t int64, v string) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, ""
 	}
 
@@ -1078,7 +1070,6 @@ func (c *stringDescendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadStringBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -1248,7 +1239,6 @@ func (c *booleanAscendingCursor) peekCache() (t int64, v bool) {
 // peekTSM returns the current time/value from tsm.
 func (c *booleanAscendingCursor) peekTSM() (t int64, v bool) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, false
 	}
 
@@ -1302,7 +1292,6 @@ func (c *booleanAscendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadBooleanBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -1360,7 +1349,6 @@ func (c *booleanDescendingCursor) peekCache() (t int64, v bool) {
 // peekTSM returns the current time/value from tsm.
 func (c *booleanDescendingCursor) peekTSM() (t int64, v bool) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, false
 	}
 
@@ -1414,7 +1402,6 @@ func (c *booleanDescendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.ReadBooleanBlock(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0

tsdb/engine/tsm1/iterator.gen.go.tmpl

@@ -239,7 +239,6 @@ func (c *{{.name}}AscendingCursor) peekCache() (t int64, v {{.Type}}) {
 // peekTSM returns the current time/value from tsm.
 func (c *{{.name}}AscendingCursor) peekTSM() (t int64, v {{.Type}}) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, {{.Nil}}
 	}
 
@@ -293,7 +292,6 @@ func (c *{{.name}}AscendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.Read{{.Name}}Block(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0
@@ -351,7 +349,6 @@ func (c *{{.name}}DescendingCursor) peekCache() (t int64, v {{.Type}}) {
 // peekTSM returns the current time/value from tsm.
 func (c *{{.name}}DescendingCursor) peekTSM() (t int64, v {{.Type}}) {
 	if c.tsm.pos < 0 || c.tsm.pos >= len(c.tsm.values) {
-		c.tsm.keyCursor.Close()
 		return tsdb.EOF, {{.Nil}}
 	}
 
@@ -405,7 +402,6 @@ func (c *{{.name}}DescendingCursor) nextTSM() {
 		c.tsm.keyCursor.Next()
 		c.tsm.values, _ = c.tsm.keyCursor.Read{{.Name}}Block(c.tsm.buf)
 		if len(c.tsm.values) == 0 {
-			c.tsm.keyCursor.Close()
 			return
 		}
 		c.tsm.pos = 0