1728

Committed 03 Oct 2023 04:48PM UTC coverage: 91.662% (+0.001%) from 91.661%

Build # 1728

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web-flow

Commit Message

fix comment to better reflect async open logic (#7025)

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94302 of 173442 branches covered (0.0%)

5 of 5 new or added lines in 1 file covered. (100.0%)

98 existing lines in 17 files now uncovered.

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76.32

/src/realm/alloc.cpp

/*************************************************************************
 *
 * Copyright 2016 Realm Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **************************************************************************/

#include <cerrno>
#include <cstdlib>
#include <stdexcept>
#include <algorithm>

#include <realm/array.hpp>
#include <realm/alloc_slab.hpp>
#include <realm/group.hpp>

using namespace realm;


namespace {

/// For use with free-standing objects (objects that are not part of a
/// Realm group)
///
/// Note that it is essential that this class is stateless as it may
/// be used by multiple threads. Although it has m_replication, this
/// is not a problem, as there is no way to modify it, so it will
/// remain zero.
class DefaultAllocator : public realm::Allocator {
public:
    DefaultAllocator()
    {
        m_baseline = 0;
    }

    MemRef do_alloc(const size_t size) override
    {
        char* addr = static_cast<char*>(::malloc(size));
        if (REALM_UNLIKELY(REALM_COVER_NEVER(!addr))) {
            // LCOV_EXCL_START
            REALM_ASSERT_DEBUG(errno == ENOMEM);
            throw std::bad_alloc();
            // LCOV_EXCL_STOP
        }
#if REALM_ENABLE_ALLOC_SET_ZERO
        std::fill(addr, addr + size, 0);
#endif
        return MemRef(addr, reinterpret_cast<size_t>(addr), *this);
    }

    MemRef do_realloc(ref_type, char* addr, size_t old_size, size_t new_size) override
    {
        char* new_addr = static_cast<char*>(::realloc(const_cast<char*>(addr), new_size));
        if (REALM_UNLIKELY(REALM_COVER_NEVER(!new_addr))) {
            // LCOV_EXCL_START
            REALM_ASSERT_DEBUG(errno == ENOMEM);
            throw std::bad_alloc();
            // LCOV_EXCL_STOP
        }
#if REALM_ENABLE_ALLOC_SET_ZERO
        std::fill(new_addr + old_size, new_addr + new_size, 0);
#else
        static_cast<void>(old_size);
#endif
        return MemRef(new_addr, reinterpret_cast<size_t>(new_addr), *this);
    }

    void do_free(ref_type, char* addr) override
    {
        ::free(addr);
    }

    char* do_translate(ref_type ref) const noexcept override
    {
        return reinterpret_cast<char*>(ref);
    }

    void verify() const override {}
    void get_or_add_xover_mapping(RefTranslation&, size_t, size_t, size_t) override
    {
        REALM_ASSERT(false);
    }
};

// This variable is declared such that get_default() can return it. It could be a static local variable, but
// Valgrind/Helgrind gives a false error report because it doesn't recognize gcc's static variable initialization
// mutex
DefaultAllocator default_alloc;

} // anonymous namespace

namespace realm {

Allocator& Allocator::get_default() noexcept
{
    return default_alloc;
}

// This function is called to handle translation of a ref which is above the limit for its
// memory mapping. This requires one of three:
// * bumping the limit of the mapping. (if the entire array is inside the mapping)
// * adding a cross-over mapping. (if the array crosses a mapping boundary)
// * using an already established cross-over mapping. (ditto)
// this can proceed concurrently with other calls to translate()
char* Allocator::translate_less_critical(RefTranslation* ref_translation_ptr, ref_type ref) const noexcept
{
    size_t idx = get_section_index(ref);
    RefTranslation& txl = ref_translation_ptr[idx];
    size_t offset = ref - get_section_base(idx);
    char* addr = txl.mapping_addr + offset;
#if REALM_ENABLE_ENCRYPTION
    realm::util::encryption_read_barrier(addr, NodeHeader::header_size, txl.encrypted_mapping, nullptr);
#endif
    auto size = NodeHeader::get_byte_size_from_header(addr);
    bool crosses_mapping = offset + size > (1 << section_shift);
    // Move the limit on use of the existing primary mapping.
    // Take into account that another thread may attempt to change / have changed it concurrently,
    size_t lowest_possible_xover_offset = txl.lowest_possible_xover_offset.load(std::memory_order_relaxed);
    auto new_lowest_possible_xover_offset = offset + (crosses_mapping ? 0 : size);
    while (new_lowest_possible_xover_offset > lowest_possible_xover_offset) {
        if (txl.lowest_possible_xover_offset.compare_exchange_weak(
                lowest_possible_xover_offset, new_lowest_possible_xover_offset, std::memory_order_relaxed))
            break;
    }
    if (REALM_LIKELY(!crosses_mapping)) {
        // Array fits inside primary mapping, no new mapping needed.
#if REALM_ENABLE_ENCRYPTION
        realm::util::encryption_read_barrier(addr, size, txl.encrypted_mapping, nullptr);
#endif
        return addr;
    }
    else {
        // we need a cross-over mapping. If one is already established, use that.
        auto xover_mapping_addr = txl.xover_mapping_addr.load(std::memory_order_acquire);
        if (!xover_mapping_addr) {
            // we need to establish a xover mapping - or wait for another thread to finish
            // establishing one:
            const_cast<Allocator*>(this)->get_or_add_xover_mapping(txl, idx, offset, size);
            // reload (can be relaxed since the call above synchronizes on a mutex)
            xover_mapping_addr = txl.xover_mapping_addr.load(std::memory_order_relaxed);
        }
        // array is now known to be inside the established xover mapping:
        addr = xover_mapping_addr + (offset - txl.xover_mapping_base);
#if REALM_ENABLE_ENCRYPTION
        realm::util::encryption_read_barrier(addr, size, txl.xover_encrypted_mapping, nullptr);
#endif
        return addr;
    }
}
} // namespace realm

1	/*************************************************************************
2	*
3	* Copyright 2016 Realm Inc.
4	*
5	* Licensed under the Apache License, Version 2.0 (the "License");
6	* you may not use this file except in compliance with the License.
7	* You may obtain a copy of the License at
8	*
9	* http://www.apache.org/licenses/LICENSE-2.0
10	*
11	* Unless required by applicable law or agreed to in writing, software
12	* distributed under the License is distributed on an "AS IS" BASIS,
13	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14	* See the License for the specific language governing permissions and
15	* limitations under the License.
16	*
17	**************************************************************************/
18
19	#include <cerrno>
20	#include <cstdlib>
21	#include <stdexcept>
22	#include <algorithm>
23
24	#include <realm/array.hpp>
25	#include <realm/alloc_slab.hpp>
26	#include <realm/group.hpp>
27
28	using namespace realm;
29
30
31	namespace {
32
33	/// For use with free-standing objects (objects that are not part of a
34	/// Realm group)
35	///
36	/// Note that it is essential that this class is stateless as it may
37	/// be used by multiple threads. Although it has m_replication, this
38	/// is not a problem, as there is no way to modify it, so it will
39	/// remain zero.
40	class DefaultAllocator : public realm::Allocator {
41	public:
42	DefaultAllocator()
43	{	24✔
44	m_baseline = 0;	24✔
45	}	24✔
46
47	MemRef do_alloc(const size_t size) override
48	{	10,283,043✔
49	char* addr = static_cast<char*>(::malloc(size));	10,283,043✔
50	if (REALM_UNLIKELY(REALM_COVER_NEVER(!addr))) {	10,283,043✔
51	// LCOV_EXCL_START
52	REALM_ASSERT_DEBUG(errno == ENOMEM);	×
53	throw std::bad_alloc();	×
54	// LCOV_EXCL_STOP
55	}	×
56	#if REALM_ENABLE_ALLOC_SET_ZERO
57	std::fill(addr, addr + size, 0);
58	#endif
59	return MemRef(addr, reinterpret_cast<size_t>(addr), *this);	10,283,043✔
60	}	10,283,043✔
61
62	MemRef do_realloc(ref_type, char* addr, size_t old_size, size_t new_size) override
63	{	1,527,879✔
64	char* new_addr = static_cast<char>(::realloc(const_cast<char>(addr), new_size));	1,527,879✔
65	if (REALM_UNLIKELY(REALM_COVER_NEVER(!new_addr))) {	1,527,879✔
66	// LCOV_EXCL_START
67	REALM_ASSERT_DEBUG(errno == ENOMEM);	×
68	throw std::bad_alloc();	×
69	// LCOV_EXCL_STOP
70	}	×
71	#if REALM_ENABLE_ALLOC_SET_ZERO
72	std::fill(new_addr + old_size, new_addr + new_size, 0);
73	#else
74	static_cast<void>(old_size);	1,527,879✔
75	#endif	1,527,879✔
76	return MemRef(new_addr, reinterpret_cast<size_t>(new_addr), *this);	1,527,879✔
77	}	1,527,879✔
78
79	void do_free(ref_type, char* addr) override
80	{	10,317,168✔
81	::free(addr);	10,317,168✔
82	}	10,317,168✔
83
84	char* do_translate(ref_type ref) const noexcept override
85	{	170,058,639✔
86	return reinterpret_cast<char*>(ref);	170,058,639✔
87	}	170,058,639✔
88
89	void verify() const override {}	×
90	void get_or_add_xover_mapping(RefTranslation&, size_t, size_t, size_t) override
91	{	×
92	REALM_ASSERT(false);	×
93	}	×
94	};
95
96	// This variable is declared such that get_default() can return it. It could be a static local variable, but
97	// Valgrind/Helgrind gives a false error report because it doesn't recognize gcc's static variable initialization
98	// mutex
99	DefaultAllocator default_alloc;
100
101	} // anonymous namespace
102
103	namespace realm {
104
105	Allocator& Allocator::get_default() noexcept
106	{	9,453,429✔
107	return default_alloc;	9,453,429✔
108	}	9,453,429✔
109
110	// This function is called to handle translation of a ref which is above the limit for its
111	// memory mapping. This requires one of three:
112	// * bumping the limit of the mapping. (if the entire array is inside the mapping)
113	// * adding a cross-over mapping. (if the array crosses a mapping boundary)
114	// * using an already established cross-over mapping. (ditto)
115	// this can proceed concurrently with other calls to translate()
116	char* Allocator::translate_less_critical(RefTranslation* ref_translation_ptr, ref_type ref) const noexcept
117	{	430,335✔
118	size_t idx = get_section_index(ref);	430,335✔
119	RefTranslation& txl = ref_translation_ptr[idx];	430,335✔
120	size_t offset = ref - get_section_base(idx);	430,335✔
121	char* addr = txl.mapping_addr + offset;	430,335✔
122	#if REALM_ENABLE_ENCRYPTION	430,335✔
123	realm::util::encryption_read_barrier(addr, NodeHeader::header_size, txl.encrypted_mapping, nullptr);	430,335✔
124	#endif	430,335✔
125	auto size = NodeHeader::get_byte_size_from_header(addr);	430,335✔
126	bool crosses_mapping = offset + size > (1 << section_shift);	430,335✔
127	// Move the limit on use of the existing primary mapping.	207,171✔
128	// Take into account that another thread may attempt to change / have changed it concurrently,	207,171✔
129	size_t lowest_possible_xover_offset = txl.lowest_possible_xover_offset.load(std::memory_order_relaxed);	430,335✔
130	auto new_lowest_possible_xover_offset = offset + (crosses_mapping ? 0 : size);	430,332✔
131	while (new_lowest_possible_xover_offset > lowest_possible_xover_offset) {	430,353✔
132	if (txl.lowest_possible_xover_offset.compare_exchange_weak(	430,287✔
133	lowest_possible_xover_offset, new_lowest_possible_xover_offset, std::memory_order_relaxed))	430,287✔
134	break;	430,269✔
135	}	430,287✔
136	if (REALM_LIKELY(!crosses_mapping)) {	430,335✔
137	// Array fits inside primary mapping, no new mapping needed.	207,171✔
138	#if REALM_ENABLE_ENCRYPTION	430,335✔
139	realm::util::encryption_read_barrier(addr, size, txl.encrypted_mapping, nullptr);	430,335✔
140	#endif	430,335✔
141	return addr;	430,335✔
142	}	430,335✔
UNCOV 143	else {	×
144	// we need a cross-over mapping. If one is already established, use that.
UNCOV 145	auto xover_mapping_addr = txl.xover_mapping_addr.load(std::memory_order_acquire);	×
146	if (!xover_mapping_addr) {	6✔
147	// we need to establish a xover mapping - or wait for another thread to finish	3✔
148	// establishing one:	3✔
149	const_cast<Allocator*>(this)->get_or_add_xover_mapping(txl, idx, offset, size);	6✔
150	// reload (can be relaxed since the call above synchronizes on a mutex)	3✔
151	xover_mapping_addr = txl.xover_mapping_addr.load(std::memory_order_relaxed);	6✔
152	}	6✔
153	// array is now known to be inside the established xover mapping:
UNCOV 154	addr = xover_mapping_addr + (offset - txl.xover_mapping_base);	×
UNCOV 155	#if REALM_ENABLE_ENCRYPTION	×
UNCOV 156	realm::util::encryption_read_barrier(addr, size, txl.xover_encrypted_mapping, nullptr);	×
UNCOV 157	#endif	×
UNCOV 158	return addr;	×
UNCOV 159	}	×
160	}	430,335✔
161	} // namespace realm

realm / realm-core / 1728

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