tree 3de9c83d73bb51dbd1514145fd3380799bc5563f
parent d46d081895ada3ab411996dc3a681f796f4a0926
author Brandon Kim <brandonkim@google.com> 1565390333 -0700
committer Brandon Kim <brandonkim@google.com> 1620414551 +0000

sensor: Implement sensor "ASYNC_READ_TIMEOUT"

This change will prevent sensors from blocking all other sensor reads
and D-Bus if they do not report failures quickly enough.

If "ASYNC_READ_TIMEOUT" environment variable is defined in the
sensor's config file for a key_type, the sensor read will be
asynchronous with timeout set in milliseconds.

For example for "sensor1":
ASYNC_READ_TIMEOUT_sensor1="1000"  // Timeout will be set to 1 sec

If the read times out, the sensor read will be skipped and the
sensor's functional property will be set to 'false'. Timed out futures
will be placed in a map to prevent their destructor from running and
blocking until the read completes (limitation of std::async).

Tested: This patch has been running downstream for over a year to
        solve a slow I2C sensor reads causing IPMI slowdown.

Change-Id: I3d9ed4d5c9cc87d3196fc281451834f3001d0b48
Signed-off-by: Brandon Kim <brandonkim@google.com>