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456 lines
17 KiB
456 lines
17 KiB
PACKAGE DOCUMENTATION
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package kstat
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import "github.com/siebenmann/go-kstat"
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Package kstat provides a Go interface to the Solaris/OmniOS kstat(s)
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system for user-level access to a lot of kernel statistics. For more
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documentation on kstats, see kstat(1) and kstat(3kstat).
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The package can retrieve what are called 'named' kstat statistics, IO
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statistics, and the most common additional types of 'raw' statistics,
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which covers almost all kstats you will normally find in the kernel. You
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can see the names and types of other kstats, but not currently retrieve
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data for them. Named statistics are the most common type for general
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information; IO statistics are exported by disks and some other things.
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Supported additional raw kstats are unix:0:sysinfo, unix:0:vminfo,
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unix:0:var, and mnt:*:mntinfo.
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General usage for named statistics: call Open() to obtain a Token, then
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call GetNamed() on it to obtain Named(s) for specific statistics. Note
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that this always gives you the very latest value for the statistic. If
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you want a number of statistics from the same module:inst:name triplet
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(eg several network counters from the same network interface) and you
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want them to all have been gathered at the same time, you need to call
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.Lookup() to obtain a KStat and then repeatedly call its .GetNamed()
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(this is also slightly more efficient).
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The short version: a kstat is a collection of some related statistics,
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eg various network counters for a particular network interface. A Token
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is a handle for a collection of kstats. You go collection (Token) ->
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kstat (KStat) -> specific statistic (Named) in order to retrieve the
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value of a specific statistic.
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(IO stats are retrieved all at once with GetIO(), because they come to
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us from the kernel as one single struct so that's what you get.)
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This is a cgo-based package. Cross compilation is up to you. Goroutine
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safety is in no way guaranteed because the underlying C kstat library is
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probably not thread or goroutine safe (and there are some all-Go
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concurrency races involving .Close()).
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This package may leak memory, especially since the Solaris kstat manpage
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is not clear on the requirements here. However I believe it's reasonably
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memory safe. It's possible to totally corrupt memory with use-after-free
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errors if you do operations on kstats after calling Token.Close(),
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although we try to avoid that.
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NOTE: this package is quite young. The API may well change as I (and
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other people) gain more experience with it.
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PERFORMANCE
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In general this is not going to be as lean and mean as calling C
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directly, partly because of intrinsic CGo overheads and partly because
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we do more memory allocation and deallocation than a C program would
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(partly because we prioritize not leaking memory).
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SUPPORTED AND UNSUPPORTED KSTAT TYPES
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We support named kstats and IO kstats (KSTAT_TYPE_NAMED and
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KSTAT_TYPE_IO / kstat_io_t respectively). kstat(1) also knows about a
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number of magic specific 'raw' stats (which are generally custom C
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structs); of these we support unix:0:sysinfo, unix:0:vminfo, unix:0:var,
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and mnt:*:mntinfo for NFS filesystem mounts.
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In theory kstat supports general timer and interrupt stats. In practice
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there is no use of KSTAT_TYPE_TIMER in the current Illumos kernel source
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and very little use of KSTAT_TYPE_INTR (mostly by very old hardware
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drivers, although the vioif driver uses it too). Since I can't test
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KSTAT_TYPE_INTR stats, we don't currently support it.
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There are also a few additional KSTAT_TYPE_RAW raw stats that we don't
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support, mostly because they seem to be effectively obsolete. These
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specific raw stats can be found listed in the Illumos source code in
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cmd/stat/kstat/kstat.h in the ks_raw_lookup array. See
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cmd/stat/kstat/kstat.c for how they're interpreted. If you need access
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to one of these kstats, the KStat.CopyTo() and KStat.Raw() methods give
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you an escape hatch to roll your own. You'll probably need to use cgo to
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generate an appropriate Go struct that matches the C struct you need. My
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notes on this process may be helpful:
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https://utcc.utoronto.ca/~cks/space/blog/programming/GoCGoCompatibleStructs
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Author: Chris Siebenmann https://github.com/siebenmann/go-kstat
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Copyright: standard Go copyright.
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(If you're reading this documentation on a non-Solaris platform, you're
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probably not seeing the detailed API documentation for constants, types,
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and so on because of tooling limitations in godoc et al.)
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FUNCTIONS
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func CFieldString(src []int8) string
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CFieldString converts a (null-terminated) C string embedded in an []int8
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slice to a (Go) string. The []int8 slice is likely to come from an
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[N]int8 fixed-size field in a statistics struct. If there is no null in
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the slice, the entire slice is returned.
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(The no-null behavior is common in C APIs; a string is often allowed to
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exactly fill the field with no room for a trailing null.)
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TYPES
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type IO struct {
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Nread uint64
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Nwritten uint64
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Reads uint32
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Writes uint32
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Wtime int64
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Wlentime int64
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Wlastupdate int64
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Rtime int64
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Rlentime int64
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Rlastupdate int64
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Wcnt uint32
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Rcnt uint32
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}
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IO represents the entire collection of KStat (disk) IO statistics
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exposed by an IoStat type KStat.
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Because IO is an exact copy of the C kstat_io_t structure from the
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kernel, it does not have a Snaptime or KStat field. You must save that
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information separately if you need it, perhaps by embedded the IO struct
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as an anonymous struct in an additional struct of your own.
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type KSType int
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KSType is the type of the data in a KStat.
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const (
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RawStat KSType = C.KSTAT_TYPE_RAW
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NamedStat KSType = C.KSTAT_TYPE_NAMED
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IntrStat KSType = C.KSTAT_TYPE_INTR
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IoStat KSType = C.KSTAT_TYPE_IO
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TimerStat KSType = C.KSTAT_TYPE_TIMER
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)
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The different types of data that a KStat may contain, ie these are the
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value of a KStat.Type. We currently only support getting Named and IO
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statistics.
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func (tp KSType) String() string
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type KStat struct {
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Module string
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Instance int
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Name string
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// Class is eg 'net' or 'disk'. In kstat(1) it shows up as a
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// ':class' statistic.
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Class string
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// Type is the type of kstat.
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Type KSType
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// Creation time of a kstat in nanoseconds since sometime.
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// See gethrtime(3) and kstat(3kstat).
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Crtime int64
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// Snaptime is what kstat(1) reports as 'snaptime', the time
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// that this data was obtained. As with Crtime, it is in
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// nanoseconds since some arbitrary point in time.
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// Snaptime may not be valid until .Refresh() or .GetNamed()
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// has been called.
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Snaptime int64
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// contains filtered or unexported fields
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}
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KStat is the access handle for the collection of statistics for a
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particular module:instance:name kstat.
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func (k *KStat) AllNamed() ([]*Named, error)
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AllNamed returns an array of all named statistics for a particular
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named-type KStat. Entries are returned in no particular order.
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func (k *KStat) CopyTo(ptr interface{}) error
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CopyTo copies a RawStat KStat into a struct that you supply a pointer
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to. The size of the struct must exactly match the size of the RawStat's
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data.
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CopyStat imposes conditions on the struct that you are copying to: it
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must be composed entirely of primitive integer types with defined sizes
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(intN and uintN), or arrays and structs that ultimately only contain
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them. All fields should be exported.
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If you give CopyStat a bad argument, it generally panics.
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This API is provisional and may be changed or deleted.
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func (k *KStat) GetIO() (*IO, error)
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GetIO retrieves the IO statistics data from an IoStat type KStat. It
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always refreshes the KStat to provide current data.
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It corresponds to kstat_read() followed by getting a copy of ks_data
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(which is a kstat_io_t).
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func (k *KStat) GetMntinfo() (*Mntinfo, error)
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GetMntinfo retrieves a Mntinfo struct from a nfs:*:mntinfo KStat. It
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does not force a refresh of the KStat.
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func (k *KStat) GetNamed(name string) (*Named, error)
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GetNamed obtains a particular named statistic from a KStat. It does not
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refresh the KStat's statistics data, so multiple calls to GetNamed on a
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single KStat will get a coherent set of statistic values from it.
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It corresponds to kstat_data_lookup().
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func (k *KStat) Raw() (*Raw, error)
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Raw returns the raw byte data of a KStat. It may be called on any KStat.
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It does not refresh the KStat's data.
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func (k *KStat) Refresh() error
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Refresh the statistics data for a KStat.
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Note that this does not update any existing Named objects for statistics
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from this KStat. You must re-do .GetNamed() to get new ones in order to
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see any updates.
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Under the hood this does a kstat_read(). You don't need to call it
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explicitly before obtaining statistics from a KStat.
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func (k *KStat) String() string
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func (k *KStat) Valid() bool
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Valid returns true if a KStat is still valid after a Token.Update() call
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has returned true. If a KStat becomes invalid after an update, its
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fields remain available but you can no longer call methods on it. You
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may be able to look it up again with token.Lookup(k.Module, k.Instance,
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k.Name), although it's possible that the module:instance:name now refers
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to something else. Even if it is still the same thing, there is no
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continuity in the actual statistics once Valid becomes false; you must
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restart tracking from scratch.
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(For example, if one disk is removed from the system and another is
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added, the new disk may use the same module:instance:name as some of the
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old disk's KStats. Your .Lookup() may succeed, but what you get back is
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not in any way a continuation of the old disk's information.)
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Valid also returns false after the KStat's token has been closed.
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type Mntinfo struct {
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RProto [128]int8
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Vers uint32
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Flags uint32
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Secmod uint32
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Curread uint32
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Curwrite uint32
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Timeo int32
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Retrans int32
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Acregmin uint32
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Acregmax uint32
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Acdirmin uint32
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Acdirmax uint32
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Timers [4]struct {
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Srtt uint32
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Deviate uint32
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Rtxcur uint32
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}
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Noresponse uint32
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Failover uint32
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Remap uint32
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RCurserver [257]int8
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// contains filtered or unexported fields
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}
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Mntinfo is the kernel data from nfs:*:mntinfo, which is a 'struct
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mntinfo_kstat'. Use .Proto() and .Curserver() to get the RProto and
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RCurserver fields as strings instead of their awkward raw form.
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func (m Mntinfo) Curserver() string
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Curserver returns a Mntinfo RCurserver as a string.
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func (m Mntinfo) Proto() string
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Proto returns a Mntinfo RProto as a string.
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type Named struct {
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Name string
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Type NamedType
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// Only one of the following values is valid; the others are zero
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// values.
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//
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// StringVal holds the value for both CharData and String Type(s).
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StringVal string
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IntVal int64
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UintVal uint64
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// The Snaptime this Named was obtained. Note that while you
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// use the parent KStat's Crtime, you cannot use its Snaptime.
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// The KStat may have been refreshed since this Named was
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// created, which updates the Snaptime.
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Snaptime int64
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// Pointer to the parent KStat, for access to the full name
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// and the crtime associated with this Named.
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KStat *KStat
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}
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Named represents a particular kstat named statistic, ie the full
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module:instance:name:statistic
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and its current value.
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Name and Type are always valid, but only one of StringVal, IntVal, or
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UintVal is valid for any particular statistic; which one is valid is
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determined by its Type. Generally you'll already know what type a given
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named kstat statistic is; I don't believe Solaris changes their type
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once they're defined.
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func (ks *Named) String() string
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type NamedType int
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NamedType represents the various types of named kstat statistics.
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const (
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CharData NamedType = C.KSTAT_DATA_CHAR
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Int32 NamedType = C.KSTAT_DATA_INT32
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Uint32 NamedType = C.KSTAT_DATA_UINT32
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Int64 NamedType = C.KSTAT_DATA_INT64
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Uint64 NamedType = C.KSTAT_DATA_UINT64
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String NamedType = C.KSTAT_DATA_STRING
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)
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The different types of data that a named kstat statistic can be (ie,
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these are the potential values of Named.Type).
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func (tp NamedType) String() string
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type Raw struct {
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Data []byte
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Ndata uint64
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Snaptime int64
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KStat *KStat
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}
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Raw is the raw data of a KStat. The actual bytes are in Data; Ndata is
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kstat_t.ks_ndata, and is not normally useful.
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Note that with RawStat KStats, it turns out that Ndata == len(Data).
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This is contrary to its meaning for other types of kstats.
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type Sysinfo struct {
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Updates uint32
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Runque uint32
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Runocc uint32
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Swpque uint32
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Swpocc uint32
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Waiting uint32
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}
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Sysinfo is the data from unix:0:sysinfo, which is a sysinfo_t.
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type Token struct {
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// contains filtered or unexported fields
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}
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Token is an access token for obtaining kstats.
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func Open() (*Token, error)
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Open returns a kstat Token that is used to obtain kstats. It corresponds
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to kstat_open(). You should call .Close() when you're done and then not
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use any KStats or Nameds obtained through this token.
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(Failing to call .Close() will cause memory leaks.)
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func (t *Token) All() []*KStat
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All returns an array of all available KStats.
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(It has no error return because due to how kstats are implemented, it
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cannot fail.)
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func (t *Token) Close() error
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Close a kstat access token. A closed token cannot be used for anything
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and cannot be reopened.
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After a Token has been closed it remains safe to look at fields on KStat
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and Named objects obtained through the Token, but it is not safe to call
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methods on them other than String(); doing so may cause memory
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corruption, although we try to avoid that.
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This corresponds to kstat_close().
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func (t *Token) GetNamed(module string, instance int, name, stat string) (*Named, error)
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GetNamed obtains the Named representing a particular (named) kstat
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module:instance:name:statistic statistic. It always returns current data
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for the kstat statistic, even if it's called repeatedly for the same
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statistic.
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It is equivalent to .Lookup() then KStat.GetNamed().
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func (t *Token) Lookup(module string, instance int, name string) (*KStat, error)
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Lookup looks up a particular kstat. module and name may be "" and
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instance may be -1 to mean 'the first one that kstats can find'. It also
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refreshes (or retrieves) the kstat's data and thus sets Snaptime.
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Lookup() corresponds to kstat_lookup() *plus kstat_read()*.
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func (tok *Token) Sysinfo() (*KStat, *Sysinfo, error)
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Sysinfo returns the KStat and the statistics from unix:0:sysinfo. It
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always returns a current, refreshed copy.
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func (t *Token) Update() (bool, error)
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Update synchronizes the Token to the current state of available kernel
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kstats, returning true if the kernel's list of available kstats changed
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and false otherwise. If there have been no changes in the kernel's kstat
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list, all KStats remain valid. If there was a kstat update, some or all
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of the KStats obtained through the Token may now be invalid. Some of the
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now-invalid KStats may still exist and be the same thing, but if so they
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will have to be looked up again.
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(This happens if, for example, a device disappears and then reappears.
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At the kernel level, the device's kstat is deleted when it disappears
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and then is recreated when it reappears; the kernel considers the
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recreated version to be a different kstat, although it has the same
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module:instance:name. Note that the same module:instance:name still
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existing does not guarantee that the kstat is for the same thing; one
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disk might have removed and then an entirely different new disk added.)
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Update corresponds to kstat_chain_update().
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func (tok *Token) Var() (*KStat, *Var, error)
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Var returns the KStat and the statistics from unix:0:var. It always
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returns a current, refreshed copy.
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func (tok *Token) Vminfo() (*KStat, *Vminfo, error)
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Vminfo returns the KStat and the statistics from unix:0:vminfo. It
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always returns a current, refreshed copy.
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type Var struct {
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Buf int32
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Call int32
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Proc int32
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Maxupttl int32
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Nglobpris int32
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Maxsyspri int32
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Clist int32
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Maxup int32
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Hbuf int32
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Hmask int32
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Pbuf int32
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Sptmap int32
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Maxpmem int32
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Autoup int32
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Bufhwm int32
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}
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Var is the data from unix:0:var, which is a 'struct var'.
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type Vminfo struct {
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Freemem uint64
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Resv uint64
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Alloc uint64
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Avail uint64
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Free uint64
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Updates uint64
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}
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Vminfo is the data from unix:0:vminfo, which is a vminfo_t.
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SUBDIRECTORIES
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cmd
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gen
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