Documentation
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Overview ¶
Package vm provides a compiler and virtual machine environment for executing mtail programs.
Index ¶
- Constants
- Variables
- func Check(node node) error
- func CodeGen(name string, ast node) (*object, error)
- func MergePosition(a, b *position) *position
- func Parse(name string, input io.Reader) (node, error)
- func Walk(v Visitor, node node)
- type ErrorList
- type Loader
- type LoaderOptions
- type Options
- type SymbolClass
- type SymbolTable
- type Type
- type Unparser
- type VM
- type Visitor
Constants ¶
const EOF = 0
Variables ¶
var ( // ProgLoads counts the number of program load events. ProgLoads = expvar.NewMap("prog_loads_total") // ProgLoadErrors counts the number of program load errors. ProgLoadErrors = expvar.NewMap("prog_load_errors") )
var ( // LineCount counts the number of lines read by the virtual machine engine from the input channel. LineCount = expvar.NewInt("line_count") )
Functions ¶
func Check ¶
func Check(node node) error
Check performs a semantic check of the ast node, and returns a boolean indicating OK; if ok is not true, then error is a list of errors found.
func MergePosition ¶
func MergePosition(a, b *position) *position
Types ¶
type ErrorList ¶
type ErrorList []*compileError
ErrorList contains a list of compile errors.
type Loader ¶
type Loader struct {
VMsDone chan struct{} // Notify mtail when all running VMs are shutdown.
// contains filtered or unexported fields
}
Loader handles the lifecycle of programs and virtual machines, by watching the configured program source directory, compiling changes to programs, and managing the running virtual machines that receive input from the lines channel.
func NewLoader ¶
func NewLoader(o LoaderOptions) (*Loader, error)
NewLoader creates a new program loader. It takes a filesystem watcher and a filesystem interface as arguments. If fs is nil, it will use the default filesystem interface.
func (*Loader) CompileAndRun ¶
CompileAndRun compiles a program read from the input, starting execution if it succeeds. If an existing virtual machine of the same name already exists, the previous virtual machine is terminated and the new loaded over it. If the new program fails to compile, any existing virtual machine with the same name remains running.
func (*Loader) LoadProg ¶
LoadProg loads or reloads a program from the path specified. The name of the program is the basename of the file.
func (*Loader) LoadProgs ¶
LoadProgs loads all programs in a directory and starts watching the directory for filesystem changes. The total number of program errors is returned.
func (*Loader) UnloadProgram ¶
UnloadProgram removes the named program from the watcher to prevent future updates, and terminates any currently running VM goroutine.
type LoaderOptions ¶
type LoaderOptions struct {
Store *metrics.Store
Lines <-chan string
W watcher.Watcher // Not required, will use watcher.LogWatcher if zero.
FS afero.Fs // Not required, will use afero.OsFs if zero.
CompileOnly bool
DumpBytecode bool
SyslogUseCurrentYear bool
}
LoaderOptions contains the required and optional parameters for creating a new Loader.
type Options ¶
type Options struct {
CompileOnly bool // Do not start the program after compilation.
SyslogUseCurrentYear bool // Use the current year if no year is present in the log file timestamp.
}
Options contains all the parameters that affect the behaviour of the compiler.
type SymbolClass ¶
type SymbolClass int
const ( IDSymbol SymbolClass = iota // Identifiers CaprefSymbol // Capture group references DefSymbol // Definitions )
symtype enumerates the types of symbols found in the program text.
type SymbolTable ¶
type SymbolTable []*scope
func (*SymbolTable) Add ¶
func (s *SymbolTable) Add(name string, class SymbolClass, loc *position) (sym *symbol)
func (*SymbolTable) CurrentScope ¶
func (s *SymbolTable) CurrentScope() *scope
func (*SymbolTable) EnterScope ¶
func (s *SymbolTable) EnterScope(sc *scope) *scope
func (*SymbolTable) ExitScope ¶
func (s *SymbolTable) ExitScope()
func (*SymbolTable) Lookup ¶
func (s *SymbolTable) Lookup(name string, class SymbolClass) (*symbol, bool)
type Unparser ¶
type Unparser struct {
// contains filtered or unexported fields
}
Unparser is for converting program syntax trees back to program text.
func (*Unparser) Unparse ¶
Unparse begins the unparsing of the syntax tree, returning the program text as a single string.
func (*Unparser) VisitAfter ¶
func (u *Unparser) VisitAfter(n node)
func (*Unparser) VisitBefore ¶
type VM ¶
type VM struct {
// contains filtered or unexported fields
}
VM describes the virtual machine for each program. It contains virtual segments of the executable bytecode, constant data (string and regular expressions), mutable state (metrics), and a stack for the current thread of execution.
func Compile ¶
Compile compiles a program from the input into a virtual machine or a list of compile errors. It takes the program's name and the metric store as additional arguments to build the virtual machine.
func New ¶
New creates a new virtual machine with the given name, and compiler artifacts for executable and data segments.
func (*VM) DumpByteCode ¶
DumpByteCode emits the program disassembly and data to standard out.
Source Files