README
¶
Type and Pointer Analysis to-do list
====================================
Alan Donovan <adonovan@google.com>
Overall design
--------------
We should re-run the type and pointer analyses periodically,
as we do with the indexer.
Version skew: how to mitigate the bad effects of stale URLs in old pages?
We could record the file's length/CRC32/mtime in the go/loader, and
refuse to decorate it with links unless they match at serving time.
Use the VFS mechanism when (a) enumerating packages and (b) loading
them. (Requires planned changes to go/loader.)
Future work: shard this using map/reduce for larger corpora.
Testing: how does one test that a web page "looks right"?
Bugs
----
(*ssa.Program).Create requires transitively error-free packages. We
can make this more robust by making the requirement transitively free
of "hard" errors; soft errors are fine.
Markup of compiler errors is slightly buggy because they overlap with
other selections (e.g. Idents). Fix.
User Interface
--------------
CALLGRAPH:
- Add a search box: given a search node, expand path from each entry
point to it.
- Cause hovering over a given node to highlight that node, and all
nodes that are logically identical to it.
- Initially expand the callgraph trees (but not their toggle divs).
CALLEES:
- The '(' links are not very discoverable. Highlight them?
Type info:
- In the source viewer's lower pane, use a toggle div around the
IMPLEMENTS and METHODSETS lists, like we do in the pacakge view.
Only expand them initially if short.
- Include IMPLEMENTS and METHOD SETS information in search index.
- URLs in IMPLEMENTS/METHOD SETS always link to source, even from the
package docs view. This makes sense for links to non-exported
types, but links to exported types and funcs should probably go to
other package docs.
- Suppress toggle divs for empty method sets.
Misc:
- The [X] button in the lower pane is subject to scrolling.
- Should the lower pane be floating? An iframe?
When we change document.location by clicking on a link, it will go away.
How do we prevent that (a la Gmail's chat windows)?
- Progress/status: for each file, display its analysis status, one of:
- not in analysis scope
- type analysis running...
- type analysis complete
(+ optionally: there were type errors in this file)
And if PTA requested:
- type analysis complete; PTA not attempted due to type errors
- PTA running...
- PTA complete
- Scroll the selection into view, e.g. the vertical center, or better
still, under the pointer (assuming we have a mouse).
More features
-------------
Display the REFERRERS relation? (Useful but potentially large.)
Display the INSTANTIATIONS relation? i.e. given a type T, show the set of
syntactic constructs that can instantiate it:
var x T
x := T{...}
x = new(T)
x = make([]T, n)
etc
+ all INSTANTIATIONS of all S defined as struct{t T} or [n]T
(Potentially a lot of information.)
(Add this to oracle too.)
Optimisations
-------------
Each call to addLink takes a (per-file) lock. The locking is
fine-grained so server latency isn't terrible, but overall it makes
the link computation quite slow. Batch update might be better.
Memory usage is now about 1.5GB for GOROOT + go.tools. It used to be 700MB.
Optimize for time and space. The main slowdown is the network I/O
time caused by an increase in page size of about 3x: about 2x from
HTML, and 0.7--2.1x from JSON (unindented vs indented). The JSON
contains a lot of filenames (e.g. 820 copies of 16 distinct
filenames). 20% of the HTML is L%d spans (now disabled). The HTML
also contains lots of tooltips for long struct/interface types.
De-dup or just abbreviate? The actual formatting is very fast.
Documentation
¶
Overview ¶
Package analysis performs type and pointer analysis and generates mark-up for the Go source view.
The Run method populates a Result object by running type and (optionally) pointer analysis. The Result object is thread-safe and at all times may be accessed by a serving thread, even as it is progressively populated as analysis facts are derived.
The Result is a mapping from each godoc file URL (e.g. /src/fmt/print.go) to information about that file. The information is a list of HTML markup links and a JSON array of structured data values. Some of the links call client-side JavaScript functions that index this array.
The analysis computes mark-up for the following relations:
IMPORTS: for each ast.ImportSpec, the package that it denotes.
RESOLUTION: for each ast.Ident, its kind and type, and the location of its definition.
METHOD SETS, IMPLEMENTS: for each ast.Ident defining a named type, its method-set, the set of interfaces it implements or is implemented by, and its size/align values.
CALLERS, CALLEES: for each function declaration ('func' token), its callers, and for each call-site ('(' token), its callees.
CALLGRAPH: the package docs include an interactive viewer for the intra-package call graph of "fmt".
CHANNEL PEERS: for each channel operation make/<-/close, the set of other channel ops that alias the same channel(s).
ERRORS: for each locus of a frontend (scanner/parser/type) error, the location is highlighted in red and hover text provides the compiler error message.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type FileInfo ¶
type FileInfo struct {
Data []interface{} // JSON serializable values
Links []Link // HTML link markup
}
FileInfo holds analysis information for the source file view. Clients must not mutate it.
type Link ¶
type Link interface {
Start() int
End() int
Write(w io.Writer, _ int, start bool) // the godoc.LinkWriter signature
}
A Link is an HTML decoration of the bytes [Start, End) of a file. Write is called before/after those bytes to emit the mark-up.
type PCGNodeJSON ¶
type PCGNodeJSON struct {
Func anchorJSON
Callees []int // indices within CALLGRAPH of nodes called by this one
}
JavaScript's cgAddChild requires a global array of PCGNodeJSON called CALLGRAPH, representing the intra-package call graph. The first element is special and represents "all external callers".
type PackageInfo ¶
type PackageInfo struct {
CallGraph []*PCGNodeJSON
CallGraphIndex map[string]int
Types []*TypeInfoJSON
}
PackageInfo holds analysis information for the package view. Clients must not mutate it.
type Result ¶
type Result struct {
// contains filtered or unexported fields
}
Result contains the results of analysis. The result contains a mapping from filenames to a set of HTML links and JavaScript data referenced by the links.
func (*Result) FileInfo ¶
FileInfo returns new slices containing opaque JSON values and the HTML link markup for the specified godoc file URL. Thread-safe. Callers must not mutate the elements. It returns "zero" if no data is available.
func (*Result) PackageInfo ¶
func (res *Result) PackageInfo(importPath string) PackageInfo
PackageInfo returns new slices of JSON values for the callgraph and type info for the specified package. Thread-safe. Callers must not mutate its fields. PackageInfo returns "zero" if no data is available.
type TypeInfoJSON ¶
type TypeInfoJSON struct {
Name string // type name
Size, Align int64
Methods []anchorJSON
ImplGroups []implGroupJSON
}
JavaScript's onClickIdent() expects a TypeInfoJSON.
Source Files