_core_rustc_static/
allocations_table.rs

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1// Copyright 2023 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use heapdump_vmo::allocations_table_v1::{AllocationsTableWriter, ResourceKey};
6use zx::{self as zx, AsHandleRef, HandleBased};
7
8/// We cap the size of our backing VMO at 2 GiB, then preallocate it and map it entirely.
9/// Actual memory for each page will only be committed when we first write to that page.
10const VMO_SIZE: usize = 1 << 31;
11
12const VMO_NAME: zx::Name = zx::Name::new_lossy("heapdump-allocations");
13
14/// Tracks live allocations by storing their metadata in a dedicated VMO.
15pub struct AllocationsTable {
16    vmo: zx::Vmo,
17    writer: AllocationsTableWriter,
18}
19
20impl Default for AllocationsTable {
21    fn default() -> AllocationsTable {
22        let vmo = zx::Vmo::create(VMO_SIZE as u64).expect("failed to create allocations VMO");
23        vmo.set_name(&VMO_NAME).expect("failed to set VMO name");
24
25        let writer = AllocationsTableWriter::new(&vmo).expect("failed to create writer");
26        AllocationsTable { vmo, writer }
27    }
28}
29
30impl AllocationsTable {
31    /// Duplicate the handle to the underlying VMO.
32    pub fn share_vmo(&self) -> zx::Vmo {
33        self.vmo.duplicate_handle(zx::Rights::SAME_RIGHTS).expect("failed to share allocations VMO")
34    }
35
36    // Take a snapshot of the underlying VMO.
37    pub fn snapshot_vmo(&self) -> zx::Vmo {
38        self.vmo
39            .create_child(
40                zx::VmoChildOptions::SNAPSHOT | zx::VmoChildOptions::NO_WRITE,
41                0,
42                VMO_SIZE as u64,
43            )
44            .expect("failed to snapshot allocations VMO")
45    }
46
47    pub fn try_record_allocation(
48        &mut self,
49        address: u64,
50        size: u64,
51        thread_info_key: ResourceKey,
52        stack_trace_key: ResourceKey,
53        timestamp: zx::MonotonicInstant,
54    ) -> bool {
55        self.writer
56            .insert_allocation(address, size, thread_info_key, stack_trace_key, timestamp)
57            .expect("out of space")
58    }
59
60    pub fn update_allocation(
61        &mut self,
62        address: u64,
63        size: u64,
64        thread_info_key: ResourceKey,
65        stack_trace_key: ResourceKey,
66        timestamp: zx::MonotonicInstant,
67    ) -> u64 {
68        if let Some(old_size) = self
69            .writer
70            .replace_allocation(address, size, thread_info_key, stack_trace_key, timestamp)
71            .expect("out of space")
72        {
73            old_size
74        } else {
75            panic!("Block 0x{:x} was not allocated", address);
76        }
77    }
78
79    pub fn forget_allocation(&mut self, address: u64) -> u64 {
80        if let Some(size) = self.writer.erase_allocation(address) {
81            size
82        } else {
83            panic!("Block 0x{:x} was not allocated", address);
84        }
85    }
86}
_core_rustc_static/allocations_table.rs

_core_rustc_static/
allocations_table.rs
