[feature] Inherit resource limits from cgroups (#1336)

When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.

1 files changed, 69 insertions, 0 deletions

diff --git a/vendor/github.com/godbus/dbus/v5/doc.go b/vendor/github.com/godbus/dbus/v5/doc.go
new file mode 100644
index 000000000..ade1df951
--- /dev/null
+++ b/vendor/github.com/godbus/dbus/v5/doc.go
@@ -0,0 +1,69 @@
+/*
+Package dbus implements bindings to the D-Bus message bus system.
+
+To use the message bus API, you first need to connect to a bus (usually the
+session or system bus). The acquired connection then can be used to call methods
+on remote objects and emit or receive signals. Using the Export method, you can
+arrange D-Bus methods calls to be directly translated to method calls on a Go
+value.
+
+Conversion Rules
+
+For outgoing messages, Go types are automatically converted to the
+corresponding D-Bus types. The following types are directly encoded as their
+respective D-Bus equivalents:
+
+     Go type     | D-Bus type
+     ------------+-----------
+     byte        | BYTE
+     bool        | BOOLEAN
+     int16       | INT16
+     uint16      | UINT16
+     int         | INT32
+     uint        | UINT32
+     int32       | INT32
+     uint32      | UINT32
+     int64       | INT64
+     uint64      | UINT64
+     float64     | DOUBLE
+     string      | STRING
+     ObjectPath  | OBJECT_PATH
+     Signature   | SIGNATURE
+     Variant     | VARIANT
+     interface{} | VARIANT
+     UnixFDIndex | UNIX_FD
+
+Slices and arrays encode as ARRAYs of their element type.
+
+Maps encode as DICTs, provided that their key type can be used as a key for
+a DICT.
+
+Structs other than Variant and Signature encode as a STRUCT containing their
+exported fields. Fields whose tags contain `dbus:"-"` and unexported fields will
+be skipped.
+
+Pointers encode as the value they're pointed to.
+
+Types convertible to one of the base types above will be mapped as the
+base type.
+
+Trying to encode any other type or a slice, map or struct containing an
+unsupported type will result in an InvalidTypeError.
+
+For incoming messages, the inverse of these rules are used, with the exception
+of STRUCTs. Incoming STRUCTS are represented as a slice of empty interfaces
+containing the struct fields in the correct order. The Store function can be
+used to convert such values to Go structs.
+
+Unix FD passing
+
+Handling Unix file descriptors deserves special mention. To use them, you should
+first check that they are supported on a connection by calling SupportsUnixFDs.
+If it returns true, all method of Connection will translate messages containing
+UnixFD's to messages that are accompanied by the given file descriptors with the
+UnixFD values being substituted by the correct indices. Similarly, the indices
+of incoming messages are automatically resolved. It shouldn't be necessary to use
+UnixFDIndex.
+
+*/
+package dbus