* usr/lib/byobu/ec2_cost, usr/lib/byobu/hostname,

usr/lib/byobu/include/shutil, usr/lib/byobu/ip_address: LP: #894038
  - background all wgets, as these can be expensive (cough OpenStack cough)
  - sleep for 0.02 seconds after each wget, as most EC2 wgets take less
    than 0.01 seconds, but some might take longer
  - after backgrounded wget and sleep, attempt to read the results of the
    wget from a cache file;  if this succeeds, proceed and use it
  - if not, fail through gracefully, and pick up the results from the
    cach file on the next run

debian/changelog

@@ -10,6 +10,15 @@ byobu (4.50) unreleased; urgency=low
   * usr/share/byobu/profiles/tmux:
     - fix action bar color
   * usr/lib/byobu/include/mondrian:
+  * usr/lib/byobu/ec2_cost, usr/lib/byobu/hostname,
+    usr/lib/byobu/include/shutil, usr/lib/byobu/ip_address: LP: #894038
+    - background all wgets, as these can be expensive (cough OpenStack cough)
+    - sleep for 0.02 seconds after each wget, as most EC2 wgets take less
+      than 0.01 seconds, but some might take longer
+    - after backgrounded wget and sleep, attempt to read the results of the
+      wget from a cache file;  if this succeeds, proceed and use it
+    - if not, fail through gracefully, and pick up the results from the
+      cach file on the next run
 
  -- Dustin Kirkland <kirkland@ubuntu.com>  Fri, 18 Nov 2011 15:41:36 -0600
 

usr/lib/byobu/ec2_cost

@@ -32,18 +32,19 @@ __ec2_cost_detail() {
 }
 
 __ec2_cost() {
-	local zone type file_to_stat cpu mem rate hours tx_gb rx_gb network_cost uptime_cost total_cost interface
+	local zone type file_to_stat cpu mem rate hours tx_gb rx_gb network_cost uptime_cost total_cost interface cache="$BYOBU_RUN_DIR/cache.$BYOBU_BACKEND/ec2_cost"
 	# Try to use metadata service
 	if metadata_available; then
-		zone=$(wget -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone)
+		[ -s "$cache.zone" ] || wget -q -O "$cache.zone" http://169.254.169.254/latest/meta-data/placement/availability-zone 2>/dev/null &
-		if [ ! -r "$BYOBU_PREFIX/share/$PKG/ec2/rates.${zone%?}" ]; then
+		sleep 0.02
-			zone="us-east-1d"
+		[ -s "$cache.zone" ] && read zone < "$cache.zone"
-		fi
+		[ -r "$BYOBU_PREFIX/share/$PKG/ec2/rates.${zone%?}" ] || zone="us-east-1d"
 		. "$BYOBU_PREFIX/share/$PKG/ec2/rates.${zone%?}"
-		type=$(wget -q -O - http://169.254.169.254/latest/meta-data/instance-type | $SED -e "s/\./_/g")
+		[ -s "$cache.type" ] || wget -q -O "$cache.type" http://169.254.169.254/latest/meta-data/instance-type 2>/dev/null &
+		sleep 0.02
+		[ -s "$cache.type" ] && type=$($SED -e "s/\./_/g" "$cache.type")
 		eval rate="\$$type"
-		file_to_stat="$BYOBU_RUN_DIR/cache.$BYOBU_BACKEND/ec2_cost.instance_type"
+		file_to_stat="$cache.type"
-		[ -f "$file_to_stat" ] || wget -q -O "$file_to_stat" http://169.254.169.254/latest/meta-data/instance-type
 	fi
 	if [ -z "$rate" ]; then
 		. "$BYOBU_PREFIX/share/$PKG/ec2/rates."*

usr/lib/byobu/hostname

@@ -24,9 +24,13 @@ __hostname_detail() {
 }
 
 __hostname() {
+	local h=
 	if metadata_available; then
-		# We're in EC2, so get our public hostname
+		local cache="$BYOBU_RUN_DIR/cache.$BYOBU_BACKEND/hostname"
-		h=$(wget -q -O - http://169.254.169.254/latest/meta-data/public-hostname)
+		# Background a retrieval of our public hostname
+		wget -q -O "$cache" http://169.254.169.254/latest/meta-data/public-hostname 2>/dev/null &
+		sleep 0.02
+		[ -s "$cache" ] && read h < "$cache"
 	else
 		h=$(hostname -s 2>/dev/null || hostname)
 	fi

usr/lib/byobu/include/shutil

@@ -209,11 +209,21 @@ metadata_available() {
 	# This is really ugly.  We need a reliable, fast way of determining
 	# if a metadata service is available, that does NOT slow down non-ec2
 	# machines.
-	if [ -e /etc/ec2_version ] || [ -e /usr/sbin/update-grub-legacy-ec2 ]; then
+	local x=0 cache="$BYOBU_CONFIG_DIR/.metadata_available"
-		wget -q -O- --timeout=1 --tries=1 http://169.254.169.254 >/dev/null 2>&1
+	# First, check the cache
+	if [ -s "$cache" ]; then
+		# Metadata is non-empty, so we have metadata available
+		x=1
 	else
-		false
+		# Must seed the cache
+		if [ -e /etc/ec2_version ] || [ -e /usr/sbin/update-grub-legacy-ec2 ]; then
+			# This *looks* like a machine with metadata, so background a potentially slow check
+			wget -q -O "$cache" --timeout=10 --tries=1 http://169.254.169.254 2>/dev/null &
+			sleep 0.02
+			[ -s "$cache" ] && x=1
 		fi
+	fi
+	[ "$x" = "1" ]
 }
 
 status_freq() {

usr/lib/byobu/ip_address

@@ -26,7 +26,7 @@ __ip_address_detail() {
 }
 
 __ip_address() {
-	local interface ipaddr
+	local interface ipaddr cache="$BYOBU_RUN_DIR/cache.$BYOBU_BACKEND/ip_address"
 	# Allow interface overrides in $BYOBU_CONFIG_DIR/statusrc
 	if [ -n "$MONITORED_NETWORK" ]; then
 		interface="$MONITORED_NETWORK"
@@ -39,21 +39,29 @@ __ip_address() {
 	case "$IPV6" in
 		1|true|yes)
 			if [ "$IP_EXTERNAL" = "1" ]; then
-				ipaddr=$(wget -O- -q http://v6.ipv6-test.com/api/myip.php)
+				# Background an update
+				wget -q -O "$cache" http://v6.ipv6-test.com/api/myip.php 2>/dev/null &
+				sleep 0.02
 			else
-				ipaddr=$(LC_ALL=C /sbin/ip -6 addr list dev "$interface" scope global 2>/dev/null)
+				# Background an update
+				LC_ALL=C /sbin/ip -6 addr list dev "$interface" scope global >"$cache" 2>/dev/null &
+			fi
+			[ -s "$cache" ] && read ipaddr < "$cache"
 			# Print 'None' if we have no global address
 			[ -z "$ipaddr" ] && ipaddr="None"
 			ipaddr=${ipaddr#* inet6 }
 			ipaddr=${ipaddr%%/*}
-			fi
 		;;
 		*)
 			if [ "$IP_EXTERNAL" = "1" ]; then
-				ipaddr=$(wget -O- -q http://v4.ipv6-test.com/api/myip.php)
+				wget -q -O "$cache" http://v4.ipv6-test.com/api/myip.php 2>/dev/null &
+				sleep 0.02
+				[ -s "$cache" ] && read ipaddr < "$cache"
 			elif metadata_available; then
 				# We're in EC2, so get our public IP address
-				ipaddr=$(wget -q -O- http://169.254.169.254/latest/meta-data/public-ipv4)
+				wget -q -O "$cache" http://169.254.169.254/latest/meta-data/public-ipv4 2>/dev/null &
+				sleep 0.02
+				[ -s "$cache" ] && read ipaddr < "$cache"
 			else
 				ipaddr=$(LC_ALL=C /sbin/ip -4 addr list dev "$interface" scope global 2>/dev/null)
 				ipaddr=${ipaddr#* inet }