cmd/pprof: add Go implementation

Update #8798

This is a new implementation of pprof,
written in Go instead of in Perl.
It was written primarily by Raul Silvera and
is in use for profiling programs of all languages
inside Google.

The internal structure is a bit package-heavy,
but it matches the copy used inside Google, and
since it is in an internal directory, we can make
changes to it later if we need to.

The only "new" file here is src/cmd/pprof/pprof.go,
which stitches together the Google pprof and the
Go command libraries for object file access.

I am explicitly NOT interested in style or review
comments on the rest of the files
(that is, src/cmd/pprof/internal/...).
Those are intended to stay as close to the Google
copies as possible, like we did with the pprof Perl script.

Still to do:

- Basic tests.
- Real command documentation.
- Hook up disassemblers.

LGTM=r
R=r, bradfitz, alex.brainman, dave
CC=golang-codereviews
https://golang.org/cl/153750043

1 files changed, 213 insertions, 0 deletions

diff --git a/src/cmd/pprof/internal/plugin/plugin.go b/src/cmd/pprof/internal/plugin/plugin.go
new file mode 100644
index 0000000000..a22ec5f3c5
--- /dev/null
+++ b/src/cmd/pprof/internal/plugin/plugin.go
@@ -0,0 +1,213 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package plugin defines the plugin implementations that the main pprof driver requires.
+package plugin
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+
+	"cmd/pprof/internal/profile"
+)
+
+// A FlagSet creates and parses command-line flags.
+// It is similar to the standard flag.FlagSet.
+type FlagSet interface {
+	// Bool, Int, Float64, and String define new flags,
+	// like the functions of the same name in package flag.
+	Bool(name string, def bool, usage string) *bool
+	Int(name string, def int, usage string) *int
+	Float64(name string, def float64, usage string) *float64
+	String(name string, def string, usage string) *string
+
+	// ExtraUsage returns any additional text that should be
+	// printed after the standard usage message.
+	// The typical use of ExtraUsage is to show any custom flags
+	// defined by the specific pprof plugins being used.
+	ExtraUsage() string
+
+	// Parse initializes the flags with their values for this run
+	// and returns the non-flag command line arguments.
+	// If an unknown flag is encountered or there are no arguments,
+	// Parse should call usage and return nil.
+	Parse(usage func()) []string
+}
+
+// An ObjTool inspects shared libraries and executable files.
+type ObjTool interface {
+	// Open opens the named object file.
+	// If the object is a shared library, start is the address where
+	// it is mapped into memory in the address space being inspected.
+	Open(file string, start uint64) (ObjFile, error)
+
+	// Demangle translates a batch of symbol names from mangled
+	// form to human-readable form.
+	Demangle(names []string) (map[string]string, error)
+
+	// Disasm disassembles the named object file, starting at
+	// the start address and stopping at (before) the end address.
+	Disasm(file string, start, end uint64) ([]Inst, error)
+
+	// SetConfig configures the tool.
+	// The implementation defines the meaning of the string
+	// and can ignore it entirely.
+	SetConfig(config string)
+}
+
+// NoObjTool returns a trivial implementation of the ObjTool interface.
+// Open returns an error indicating that the requested file does not exist.
+// Demangle returns an empty map and a nil error.
+// Disasm returns an error.
+// SetConfig is a no-op.
+func NoObjTool() ObjTool {
+	return noObjTool{}
+}
+
+type noObjTool struct{}
+
+func (noObjTool) Open(file string, start uint64) (ObjFile, error) {
+	return nil, &os.PathError{Op: "open", Path: file, Err: os.ErrNotExist}
+}
+
+func (noObjTool) Demangle(name []string) (map[string]string, error) {
+	return make(map[string]string), nil
+}
+
+func (noObjTool) Disasm(file string, start, end uint64) ([]Inst, error) {
+	return nil, fmt.Errorf("disassembly not supported")
+}
+
+func (noObjTool) SetConfig(config string) {
+}
+
+// An ObjFile is a single object file: a shared library or executable.
+type ObjFile interface {
+	// Name returns the underlyinf file name, if available
+	Name() string
+
+	// Base returns the base address to use when looking up symbols in the file.
+	Base() uint64
+
+	// BuildID returns the GNU build ID of the file, or an empty string.
+	BuildID() string
+
+	// SourceLine reports the source line information for a given
+	// address in the file. Due to inlining, the source line information
+	// is in general a list of positions representing a call stack,
+	// with the leaf function first.
+	SourceLine(addr uint64) ([]Frame, error)
+
+	// Symbols returns a list of symbols in the object file.
+	// If r is not nil, Symbols restricts the list to symbols
+	// with names matching the regular expression.
+	// If addr is not zero, Symbols restricts the list to symbols
+	// containing that address.
+	Symbols(r *regexp.Regexp, addr uint64) ([]*Sym, error)
+
+	// Close closes the file, releasing associated resources.
+	Close() error
+}
+
+// A Frame describes a single line in a source file.
+type Frame struct {
+	Func string // name of function
+	File string // source file name
+	Line int    // line in file
+}
+
+// A Sym describes a single symbol in an object file.
+type Sym struct {
+	Name  []string // names of symbol (many if symbol was dedup'ed)
+	File  string   // object file containing symbol
+	Start uint64   // start virtual address
+	End   uint64   // virtual address of last byte in sym (Start+size-1)
+}
+
+// An Inst is a single instruction in an assembly listing.
+type Inst struct {
+	Addr uint64 // virtual address of instruction
+	Text string // instruction text
+	File string // source file
+	Line int    // source line
+}
+
+// A UI manages user interactions.
+type UI interface {
+	// Read returns a line of text (a command) read from the user.
+	ReadLine() (string, error)
+
+	// Print shows a message to the user.
+	// It formats the text as fmt.Print would and adds a final \n if not already present.
+	// For line-based UI, Print writes to standard error.
+	// (Standard output is reserved for report data.)
+	Print(...interface{})
+
+	// PrintErr shows an error message to the user.
+	// It formats the text as fmt.Print would and adds a final \n if not already present.
+	// For line-based UI, PrintErr writes to standard error.
+	PrintErr(...interface{})
+
+	// IsTerminal returns whether the UI is known to be tied to an
+	// interactive terminal (as opposed to being redirected to a file).
+	IsTerminal() bool
+
+	// SetAutoComplete instructs the UI to call complete(cmd) to obtain
+	// the auto-completion of cmd, if the UI supports auto-completion at all.
+	SetAutoComplete(complete func(string) string)
+}
+
+// StandardUI returns a UI that reads from standard input,
+// prints messages to standard output,
+// prints errors to standard error, and doesn't use auto-completion.
+func StandardUI() UI {
+	return &stdUI{r: bufio.NewReader(os.Stdin)}
+}
+
+type stdUI struct {
+	r *bufio.Reader
+}
+
+func (ui *stdUI) ReadLine() (string, error) {
+	os.Stdout.WriteString("(pprof) ")
+	return ui.r.ReadString('\n')
+}
+
+func (ui *stdUI) Print(args ...interface{}) {
+	ui.fprint(os.Stderr, args)
+}
+
+func (ui *stdUI) PrintErr(args ...interface{}) {
+	ui.fprint(os.Stderr, args)
+}
+
+func (ui *stdUI) IsTerminal() bool {
+	return false
+}
+
+func (ui *stdUI) SetAutoComplete(func(string) string) {
+}
+
+func (ui *stdUI) fprint(f *os.File, args []interface{}) {
+	text := fmt.Sprint(args...)
+	if !strings.HasSuffix(text, "\n") {
+		text += "\n"
+	}
+	f.WriteString(text)
+}
+
+// A Fetcher reads and returns the profile named by src.
+// It gives up after the given timeout, unless src contains a timeout override
+// (as defined by the implementation).
+// It can print messages to ui.
+type Fetcher func(src string, timeout time.Duration, ui UI) (*profile.Profile, error)
+
+// A Symbolizer annotates a profile with symbol information.
+// The profile was fetch from src.
+// The meaning of mode is defined by the implementation.
+type Symbolizer func(mode, src string, prof *profile.Profile, obj ObjTool, ui UI) error