dump_heap.py

import typing
from typing import List, Optional, Tuple, TypeVar, Callable, NamedTuple, Set, Dict, Iterator, Any
from . import ghc_heap
from .types import *
from . import closure
from .utils import CommandWithArgs, get_num_generations
from .block import get_bdescr_val, format_bdescr, heap_start, heap_end, BlockFlags
from .mut_list import collect_mut_list
import gdb

def find_blocks(sampleFreq: int = 4000) -> Iterator[Any]:
    for p in range(heap_start.addr(), heap_end.addr(), sampleFreq):
        bdVal = get_bdescr_val(Ptr(p))
        if bdVal is not None: # Block found
            bd = bdVal.dereference()
            start = int(bd['start'])
            if start != 0: # Is a valid block. Filters out memory that has been zeroed out.
                if int(bd['free']) != -1: # Is a live block. Filters out dead blocks.
                    yield bdVal

class DumpHeapCmd(CommandWithArgs):
    """ Dump the heap """
    command_name = "ghc dump"

    def build_parser(self, parser):
        pass

    def run(self, opts, from_tty) -> None:
        pass

class DumpBlocksCmd(CommandWithArgs):
    """ Dump all heap blocks """
    command_name = "ghc blocks"

    def build_parser(self, parser):
        parser.add_argument('-s', '--sample',
                            action='store', type=int, help='sample every <sample> bytes',
                            default=(4000))
        parser.add_argument('-p', '--pinned',
                            action='store_true', help='Show only pinned and large object blocks',
                            default=False)

    def run(self, opts, from_tty) -> None:
        # try to sample the heap and find blocks are ?4000bytes? so sample more frequently than that.
        count = 0
        for bdVal in find_blocks(opts.sample):
            bd = bdVal.dereference()
            flags = int(bd['flags'])
            # Check for pinned/large object if necessary.
            if (not opts.pinned) or flags & (BlockFlags.BF_PINNED | BlockFlags.BF_LARGE):
                print(format_bdescr(bdVal))
                count += 1

        print('Found %d blocks' % count)

DumpHeapCmd()
DumpBlocksCmd()