Class JEmalloc
- java.lang.Object
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- org.lwjgl.system.jemalloc.JEmalloc
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public class JEmalloc extends java.lang.Object
Native bindings to jemalloc.jemalloc is a general purpose malloc implementation that emphasizes fragmentation avoidance and scalable concurrency support. jemalloc first came into use as the FreeBSD libc allocator in 2005, and since then it has found its way into numerous applications that rely on its predictable behavior. In 2010 jemalloc development efforts broadened to include developer support features such as heap profiling, Valgrind integration, and extensive monitoring/tuning hooks. Modern jemalloc releases continue to be integrated back into FreeBSD, and therefore versatility remains critical. Ongoing development efforts trend toward making jemalloc among the best allocators for a broad range of demanding applications, and eliminating/mitigating weaknesses that have practical repercussions for real world applications.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
JEmalloc.Functions
Contains the function pointers loaded from the jemallocSharedLibrary
.
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
JEMALLOC_VERSION
The version string.static int
JEMALLOC_VERSION_BUGFIX
The bugfix version.static java.lang.String
JEMALLOC_VERSION_GID
The globally unique identifier (git commit hash).static int
JEMALLOC_VERSION_MAJOR
The major version.static int
JEMALLOC_VERSION_MINOR
The minor version.static int
JEMALLOC_VERSION_NREV
The revision number.static int
MALLCTL_ARENAS_ALL
Use as arena index in "arena.<i>.{purge,decay,dss}" and "stats.arenas.<i>.*" mallctl interfaces to select all arenas.static int
MALLCTL_ARENAS_DESTROYED
Use as arena index in "stats.arenas.<i>.*" mallctl interfaces to select destroyed arenas.static int
MALLOCX_TCACHE_NONE
Do not use a thread-specific cache (tcache).static int
MALLOCX_ZERO
Initialize newly allocated memory to contain zero bytes.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static org.lwjgl.system.SharedLibrary
getLibrary()
Returns the jemallocSharedLibrary
.static java.nio.ByteBuffer
je_aligned_alloc(long alignment, long size)
Allocatessize
bytes of memory such that the allocation's base address is an even multiple ofalignment
.static java.nio.ByteBuffer
je_calloc(long num, long size)
Allocates space fornum
objects, eachsize
bytes in length.static void
je_dallocx(java.nio.ByteBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(java.nio.DoubleBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(java.nio.FloatBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(java.nio.IntBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(java.nio.LongBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(java.nio.ShortBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_dallocx(org.lwjgl.PointerBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.ByteBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.DoubleBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.FloatBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.IntBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.LongBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(java.nio.ShortBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static void
je_free(org.lwjgl.PointerBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations.static int
je_mallctl(java.lang.CharSequence name, java.nio.ByteBuffer oldp, org.lwjgl.PointerBuffer oldlenp, java.nio.ByteBuffer newp)
Provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions.static int
je_mallctl(java.nio.ByteBuffer name, java.nio.ByteBuffer oldp, org.lwjgl.PointerBuffer oldlenp, java.nio.ByteBuffer newp)
Provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions.static int
je_mallctlbymib(org.lwjgl.PointerBuffer mib, java.nio.ByteBuffer oldp, org.lwjgl.PointerBuffer oldlenp, java.nio.ByteBuffer newp)
Similar tomallctl
, but uses MIBs instead of names.static int
je_mallctlnametomib(java.lang.CharSequence name, org.lwjgl.PointerBuffer mibp, org.lwjgl.PointerBuffer miblenp)
Provides a way to avoid repeated name lookups for applications that repeatedly query the same portion of the namespace, by translating a name to a “Management Information Base” (MIB) that can be passed repeatedly tomallctlbymib
.static int
je_mallctlnametomib(java.nio.ByteBuffer name, org.lwjgl.PointerBuffer mibp, org.lwjgl.PointerBuffer miblenp)
Provides a way to avoid repeated name lookups for applications that repeatedly query the same portion of the namespace, by translating a name to a “Management Information Base” (MIB) that can be passed repeatedly tomallctlbymib
.static java.nio.ByteBuffer
je_malloc(long size)
Allocatessize
bytes of uninitialized memory.static org.lwjgl.PointerBuffer
je_malloc_message()
Returns theje_malloc_message
variable.static void
je_malloc_stats_print(MallocMessageCallbackI write_cb, long cbopaque, java.lang.CharSequence opts)
Writes human-readable summary statistics via thewrite_cb
callback function pointer andcbopaque
data passed towrite_cb
, ormalloc_message()
ifwrite_cb
isNULL
.static void
je_malloc_stats_print(MallocMessageCallbackI write_cb, long cbopaque, java.nio.ByteBuffer opts)
Writes human-readable summary statistics via thewrite_cb
callback function pointer andcbopaque
data passed towrite_cb
, ormalloc_message()
ifwrite_cb
isNULL
.static long
je_malloc_usable_size(java.nio.ByteBuffer ptr)
Returns the usable size of the allocation pointed to byptr
.static java.nio.ByteBuffer
je_mallocx(long size, int flags)
Allocates at leastsize
bytes of memory, and returns a pointer to the base address of the allocation.static java.nio.ByteBuffer
je_nallocx(long size, int flags)
Allocates no memory, but it performs the same size computation as themallocx
function, and returns the real size of the allocation that would result from the equivalentmallocx()
function call.static int
je_posix_memalign(org.lwjgl.PointerBuffer memptr, long alignment, long size)
Allocatessize
bytes of memory such that the allocation's base address is an even multiple ofalignment
, and returns the allocation in the value pointed to bymemptr
.static java.nio.ByteBuffer
je_rallocx(java.nio.ByteBuffer ptr, long size, int flags)
Resizes the allocation atptr
to be at leastsize
bytes, and returns a pointer to the base address of the resulting allocation, which may or may not have moved from its original location.static java.nio.ByteBuffer
je_realloc(java.nio.ByteBuffer ptr, long size)
Changes the size of the previously allocated memory referenced byptr
tosize
bytes.static long
je_sallocx(java.nio.ByteBuffer ptr, int flags)
Returns the real size of the allocation atptr
.static void
je_sdallocx(java.nio.ByteBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(java.nio.DoubleBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(java.nio.FloatBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(java.nio.IntBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(java.nio.LongBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(java.nio.ShortBuffer ptr, int flags)
Sized version ofdallocx
.static void
je_sdallocx(org.lwjgl.PointerBuffer ptr, int flags)
Sized version ofdallocx
.static long
je_xallocx(java.nio.ByteBuffer ptr, long size, long extra, int flags)
Resizes the allocation atptr
in place to be at least size bytes, and returns the real size of the allocation.static int
MALLOCX_ALIGN(int a)
Align the memory allocation to start at an address that is a multiple ofa
, wherea
is a power of two.static int
MALLOCX_ARENA(int a)
Use the arena specified by the indexa
(and by necessity bypass the thread cache).static int
MALLOCX_LG_ALIGN(int la)
Align the memory allocation to start at an address that is a multiple of(1 << la)
.static int
MALLOCX_TCACHE(int tc)
Use the thread-specific cache (tcache) specified by the identifiertc
, which must have been acquired via thetcache.create
mallctl.static long
nje_aligned_alloc(long alignment, long size)
Unsafe version of:aligned_alloc
static long
nje_calloc(long num, long size)
Unsafe version of:calloc
static void
nje_dallocx(long ptr, int flags)
Unsafe version of:dallocx
static void
nje_free(long ptr)
Unsafe version of:free
static int
nje_mallctl(long name, long oldp, long oldlenp, long newp, long newlen)
Unsafe version of:mallctl
static int
nje_mallctlbymib(long mib, long miblen, long oldp, long oldlenp, long newp, long newlen)
Unsafe version of:mallctlbymib
static int
nje_mallctlnametomib(long name, long mibp, long miblenp)
Unsafe version of:mallctlnametomib
static long
nje_malloc(long size)
Unsafe version of:malloc
static void
nje_malloc_stats_print(long write_cb, long cbopaque, long opts)
Unsafe version of:malloc_stats_print
static long
nje_malloc_usable_size(long ptr)
Unsafe version of:malloc_usable_size
static long
nje_mallocx(long size, int flags)
Unsafe version of:mallocx
static long
nje_nallocx(long size, int flags)
Unsafe version of:nallocx
static int
nje_posix_memalign(long memptr, long alignment, long size)
Unsafe version of:posix_memalign
static long
nje_rallocx(long ptr, long size, int flags)
Unsafe version of:rallocx
static long
nje_realloc(long ptr, long size)
Unsafe version of:realloc
static long
nje_sallocx(long ptr, int flags)
Unsafe version of:sallocx
static void
nje_sdallocx(long ptr, long size, int flags)
Unsafe version of:sdallocx
static long
nje_xallocx(long ptr, long size, long extra, int flags)
Unsafe version of:xallocx
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Field Detail
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JEMALLOC_VERSION_MAJOR
The major version.
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JEMALLOC_VERSION_MINOR
The minor version.
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JEMALLOC_VERSION_BUGFIX
The bugfix version.
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JEMALLOC_VERSION_NREV
The revision number.
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JEMALLOC_VERSION_GID
The globally unique identifier (git commit hash).
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JEMALLOC_VERSION
The version string.
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MALLOCX_ZERO
Initialize newly allocated memory to contain zero bytes. In the growing reallocation case, the real size prior to reallocation defines the boundary between untouched bytes and those that are initialized to contain zero bytes. If this macro is absent, newly allocated memory is uninitialized.
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MALLOCX_TCACHE_NONE
Do not use a thread-specific cache (tcache). UnlessMALLOCX_TCACHE(int)
orMALLOCX_TCACHE_NONE
is specified, an automatically managed tcache will be used under many circumstances. This macro cannot be used in the sameflags
argument asMALLOCX_TCACHE(tc)
.
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MALLCTL_ARENAS_ALL
Use as arena index in "arena.<i>.{purge,decay,dss}" and "stats.arenas.<i>.*" mallctl interfaces to select all arenas.
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MALLCTL_ARENAS_DESTROYED
Use as arena index in "stats.arenas.<i>.*" mallctl interfaces to select destroyed arenas.
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Method Detail
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getLibrary
public static org.lwjgl.system.SharedLibrary getLibrary()
Returns the jemallocSharedLibrary
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je_malloc_message
public static org.lwjgl.PointerBuffer je_malloc_message()
Returns theje_malloc_message
variable.
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nje_malloc
public static long nje_malloc(long size)
Unsafe version of:malloc
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je_malloc
@Nullable public static java.nio.ByteBuffer je_malloc(long size)
Allocatessize
bytes of uninitialized memory. The allocated space is suitably aligned (after possible pointer coercion) for storage of any type of object.- Parameters:
size
- the number of bytes to allocate
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nje_calloc
public static long nje_calloc(long num, long size)
Unsafe version of:calloc
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je_calloc
@Nullable public static java.nio.ByteBuffer je_calloc(long num, long size)
Allocates space fornum
objects, eachsize
bytes in length. The result is identical to callingmalloc
with an argument ofnum * size
, with the exception that the allocated memory is explicitly initialized to zero bytes.- Parameters:
num
- the number of objects to allocatesize
- the size of each object, in bytes
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nje_posix_memalign
public static int nje_posix_memalign(long memptr, long alignment, long size)
Unsafe version of:posix_memalign
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je_posix_memalign
public static int je_posix_memalign(org.lwjgl.PointerBuffer memptr, long alignment, long size)
Allocatessize
bytes of memory such that the allocation's base address is an even multiple ofalignment
, and returns the allocation in the value pointed to bymemptr
. The requested alignment must be a power of 2 at least as large assizeof(void *)
.- Parameters:
memptr
- returns the allocated memoryalignment
- the allocation alignment, in bytessize
- the number of bytes to allocate
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nje_aligned_alloc
public static long nje_aligned_alloc(long alignment, long size)
Unsafe version of:aligned_alloc
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je_aligned_alloc
@Nullable public static java.nio.ByteBuffer je_aligned_alloc(long alignment, long size)
Allocatessize
bytes of memory such that the allocation's base address is an even multiple ofalignment
. The requested alignment must be a power of 2. Behavior is undefined ifsize
is not an integral multiple ofalignment
.- Parameters:
alignment
- the allocation alignment, in bytessize
- the number of bytes to allocate
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nje_realloc
public static long nje_realloc(long ptr, long size)
Unsafe version of:realloc
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je_realloc
@Nullable public static java.nio.ByteBuffer je_realloc(@Nullable java.nio.ByteBuffer ptr, long size)
Changes the size of the previously allocated memory referenced byptr
tosize
bytes. The contents of the memory are unchanged up to the lesser of the new and old sizes. If the new size is larger, the contents of the newly allocated portion of the memory are undefined. Upon success, the memory referenced byptr
is freed and a pointer to the newly allocated memory is returned. Note that realloc() may move the memory allocation, resulting in a different return value thanptr
. Ifptr
isNULL
, the realloc() function behaves identically to malloc() for the specified size.- Parameters:
ptr
- the previously allocated memory orNULL
size
- the number of bytes to allocate
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nje_free
public static void nje_free(long ptr)
Unsafe version of:free
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je_free
public static void je_free(@Nullable java.nio.ByteBuffer ptr) public static void je_free(@Nullable java.nio.ShortBuffer ptr) public static void je_free(@Nullable java.nio.IntBuffer ptr) public static void je_free(@Nullable java.nio.LongBuffer ptr) public static void je_free(@Nullable java.nio.FloatBuffer ptr) public static void je_free(@Nullable java.nio.DoubleBuffer ptr) public static void je_free(@Nullable org.lwjgl.PointerBuffer ptr)
Causes the allocated memory referenced byptr
to be made available for future allocations. Ifptr
isNULL
, no action occurs.- Parameters:
ptr
- the allocated memory to free
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nje_mallocx
public static long nje_mallocx(long size, int flags)
Unsafe version of:mallocx
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je_mallocx
@Nullable public static java.nio.ByteBuffer je_mallocx(long size, int flags)
Allocates at leastsize
bytes of memory, and returns a pointer to the base address of the allocation. Behavior is undefined ifsize
is 0, or if request size overflows due to size class and/or alignment constraints.- Parameters:
size
- the number of bytes to allocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_rallocx
public static long nje_rallocx(long ptr, long size, int flags)
Unsafe version of:rallocx
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je_rallocx
@Nullable public static java.nio.ByteBuffer je_rallocx(@Nullable java.nio.ByteBuffer ptr, long size, int flags)
Resizes the allocation atptr
to be at leastsize
bytes, and returns a pointer to the base address of the resulting allocation, which may or may not have moved from its original location. Behavior is undefined ifsize
is 0, or if request size overflows due to size class and/or alignment constraints.- Parameters:
ptr
- the previously allocated memory orNULL
size
- the number of bytes to allocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_xallocx
public static long nje_xallocx(long ptr, long size, long extra, int flags)
Unsafe version of:xallocx
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je_xallocx
public static long je_xallocx(@Nullable java.nio.ByteBuffer ptr, long size, long extra, int flags)
Resizes the allocation atptr
in place to be at least size bytes, and returns the real size of the allocation. Ifextra
is non-zero, an attempt is made to resize the allocation to be at least(size + extra)
bytes, though inability to allocate the extra byte(s) will not by itself result in failure to resize. Behavior is undefined ifsize
is 0, or if(size + extra > SIZE_T_MAX)
.- Parameters:
ptr
- the previously allocated memory orNULL
size
- the number of bytes to allocateextra
- the number of extra bytes to allocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_sallocx
public static long nje_sallocx(long ptr, int flags)
Unsafe version of:sallocx
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je_sallocx
public static long je_sallocx(java.nio.ByteBuffer ptr, int flags)
Returns the real size of the allocation atptr
.- Parameters:
ptr
- the allocated memory to queryflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_dallocx
public static void nje_dallocx(long ptr, int flags)
Unsafe version of:dallocx
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je_dallocx
public static void je_dallocx(java.nio.ByteBuffer ptr, int flags) public static void je_dallocx(java.nio.ShortBuffer ptr, int flags) public static void je_dallocx(java.nio.IntBuffer ptr, int flags) public static void je_dallocx(java.nio.LongBuffer ptr, int flags) public static void je_dallocx(java.nio.FloatBuffer ptr, int flags) public static void je_dallocx(java.nio.DoubleBuffer ptr, int flags) public static void je_dallocx(org.lwjgl.PointerBuffer ptr, int flags)
Causes the memory referenced byptr
to be made available for future allocations.- Parameters:
ptr
- the allocated memory to deallocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_sdallocx
public static void nje_sdallocx(long ptr, long size, int flags)
Unsafe version of:sdallocx
- Parameters:
size
- the number of bytes inptr
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je_sdallocx
public static void je_sdallocx(java.nio.ByteBuffer ptr, int flags) public static void je_sdallocx(java.nio.ShortBuffer ptr, int flags) public static void je_sdallocx(java.nio.IntBuffer ptr, int flags) public static void je_sdallocx(java.nio.LongBuffer ptr, int flags) public static void je_sdallocx(java.nio.FloatBuffer ptr, int flags) public static void je_sdallocx(java.nio.DoubleBuffer ptr, int flags) public static void je_sdallocx(org.lwjgl.PointerBuffer ptr, int flags)
Sized version ofdallocx
. The primary optimization overdallocx()
is the removal of a metadata read, which often suffers an L1 cache miss.- Parameters:
ptr
- the allocated memory to deallocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_nallocx
public static long nje_nallocx(long size, int flags)
Unsafe version of:nallocx
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je_nallocx
@Nullable public static java.nio.ByteBuffer je_nallocx(long size, int flags)
Allocates no memory, but it performs the same size computation as themallocx
function, and returns the real size of the allocation that would result from the equivalentmallocx()
function call. Behavior is undefined ifsize
is 0, or if request size overflows due to size class and/or alignment constraints.- Parameters:
size
- the number of bytes to allocateflags
- a bitfield of zero or more of theMALLOCX
macros
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nje_mallctl
public static int nje_mallctl(long name, long oldp, long oldlenp, long newp, long newlen)
Unsafe version of:mallctl
- Parameters:
newlen
- the new value length
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je_mallctl
public static int je_mallctl(java.nio.ByteBuffer name, @Nullable java.nio.ByteBuffer oldp, @Nullable org.lwjgl.PointerBuffer oldlenp, @Nullable java.nio.ByteBuffer newp) public static int je_mallctl(java.lang.CharSequence name, @Nullable java.nio.ByteBuffer oldp, @Nullable org.lwjgl.PointerBuffer oldlenp, @Nullable java.nio.ByteBuffer newp)
Provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions. The period-separatedname
argument specifies a location in a tree-structured namespace; see the MALLCTL NAMESPACE section for documentation on the tree contents. To read a value, pass a pointer viaoldp
to adequate space to contain the value, and a pointer to its length viaoldlenp
; otherwise passNULL
andNULL
. Similarly, to write a value, pass a pointer to the value vianewp
, and its length vianewlen
; otherwise passNULL
and0
.- Parameters:
name
- the namespace locationoldp
- returns a valueoldlenp
- returns the value lengthnewp
- the new value
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nje_mallctlnametomib
public static int nje_mallctlnametomib(long name, long mibp, long miblenp)
Unsafe version of:mallctlnametomib
- Parameters:
miblenp
- the number of components inmibp
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je_mallctlnametomib
public static int je_mallctlnametomib(java.nio.ByteBuffer name, org.lwjgl.PointerBuffer mibp, org.lwjgl.PointerBuffer miblenp) public static int je_mallctlnametomib(java.lang.CharSequence name, org.lwjgl.PointerBuffer mibp, org.lwjgl.PointerBuffer miblenp)
Provides a way to avoid repeated name lookups for applications that repeatedly query the same portion of the namespace, by translating a name to a “Management Information Base” (MIB) that can be passed repeatedly tomallctlbymib
. Upon successful return frommallctlnametomib()
,mibp
contains an array of*miblenp
integers, where*miblenp
is the lesser of the number of components in name and the input value of*miblenp
. Thus it is possible to pass a*miblenp
that is smaller than the number of period-separated name components, which results in a partial MIB that can be used as the basis for constructing a complete MIB. For name components that are integers (e.g. the 2 in "arenas.bin.2.size"), the corresponding MIB component will always be that integer. Therefore, it is legitimate to construct code like the following:unsigned nbins, i; size_t mib[4]; size_t len, miblen; len = sizeof(nbins); mallctl("arenas.nbins", &nbins, &len, NULL, 0); miblen = 4; mallctlnametomib("arenas.bin.0.size", mib, &miblen); for (i = 0; i < nbins; i++) { size_t bin_size; mib[2] = i; len = sizeof(bin_size); mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0); // Do something with bin_size... }
- Parameters:
name
- the namespace locationmibp
- an array of integersmiblenp
- the number of components inmibp
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nje_mallctlbymib
public static int nje_mallctlbymib(long mib, long miblen, long oldp, long oldlenp, long newp, long newlen)
Unsafe version of:mallctlbymib
- Parameters:
miblen
- the number of elements inmib
newlen
- the new value length
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je_mallctlbymib
public static int je_mallctlbymib(org.lwjgl.PointerBuffer mib, @Nullable java.nio.ByteBuffer oldp, @Nullable org.lwjgl.PointerBuffer oldlenp, @Nullable java.nio.ByteBuffer newp)
Similar tomallctl
, but uses MIBs instead of names. Seemallctlnametomib
for details.- Parameters:
mib
- a MIBoldp
- returns a valueoldlenp
- returns the value lengthnewp
- the new value
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nje_malloc_stats_print
public static void nje_malloc_stats_print(long write_cb, long cbopaque, long opts)
Unsafe version of:malloc_stats_print
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je_malloc_stats_print
public static void je_malloc_stats_print(@Nullable MallocMessageCallbackI write_cb, long cbopaque, @Nullable java.nio.ByteBuffer opts) public static void je_malloc_stats_print(@Nullable MallocMessageCallbackI write_cb, long cbopaque, @Nullable java.lang.CharSequence opts)
Writes human-readable summary statistics via thewrite_cb
callback function pointer andcbopaque
data passed towrite_cb
, ormalloc_message()
ifwrite_cb
isNULL
. This function can be called repeatedly. General information that never changes during execution can be omitted by specifying "g" as a character within theopts
string. Note thatmalloc_message()
uses themallctl*()
functions internally, so inconsistent statistics can be reported if multiple threads use these functions simultaneously. If--enable-stats
is specified during configuration, “m” and “a” can be specified to omit merged arena and per arena statistics, respectively; “b” and “l” can be specified to omit per size class statistics for bins and large objects, respectively. Unrecognized characters are silently ignored. Note that thread caching may prevent some statistics from being completely up to date, since extra locking would be required to merge counters that track thread cache operations.- Parameters:
write_cb
- the print callback, orNULL
to usemalloc_message()
cbopaque
- an opaque pointer that will be passed towrite_cb
opts
- an options string
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nje_malloc_usable_size
public static long nje_malloc_usable_size(long ptr)
Unsafe version of:malloc_usable_size
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je_malloc_usable_size
public static long je_malloc_usable_size(java.nio.ByteBuffer ptr)
Returns the usable size of the allocation pointed to byptr
. The return value may be larger than the size that was requested during allocation. Themalloc_usable_size()
function is not a mechanism for in-placerealloc
; rather it is provided solely as a tool for introspection purposes. Any discrepancy between the requested allocation size and the size reported bymalloc_usable_size()
should not be depended on, since such behavior is entirely implementation-dependent.- Parameters:
ptr
- the allocated memory to query
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MALLOCX_LG_ALIGN
public static int MALLOCX_LG_ALIGN(int la)
Align the memory allocation to start at an address that is a multiple of(1 << la)
. This macro does not validate thatla
is within the valid range.- Parameters:
la
- the alignment shift
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MALLOCX_ALIGN
public static int MALLOCX_ALIGN(int a)
Align the memory allocation to start at an address that is a multiple ofa
, wherea
is a power of two. This macro does not validate thata
is a power of 2.- Parameters:
a
- the alignment
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MALLOCX_TCACHE
public static int MALLOCX_TCACHE(int tc)
Use the thread-specific cache (tcache) specified by the identifiertc
, which must have been acquired via thetcache.create
mallctl. This macro does not validate thattc
specifies a valid identifier.- Parameters:
tc
- the thread-specific cache
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MALLOCX_ARENA
public static int MALLOCX_ARENA(int a)
Use the arena specified by the indexa
(and by necessity bypass the thread cache). This macro has no effect for huge regions, nor for regions that were allocated via an arena other than the one specified. This macro does not validate thata
specifies an arena index in the valid range.- Parameters:
a
- the arena index
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