Abstract: The present disclosure provides a data operation method, apparatus, device, and storage medium, which relates to the technical fields of distributed file system, in particular, to the technical fields of multi-version concurrency control and log-structured merge tree. The specific implementation scheme is as follows: obtaining a plurality of operation records on at least one piece of data in a file system; determining a target operation record of target data in the plurality of operation records, where the target operation record is a deletion record, and the target operation record is a latest operation record of the target data; and deleting at least one version of the target data in the file system according to the target operation record.

Abstract: A method and apparatus for renaming a file system object and a storage medium are provided. The method includes: determining a renaming type for a file system object according to a received renaming request; determining, according to the renaming type, data processing operations respectively corresponding to multiple servers, wherein the multiple servers include a first server storing structure information of a directory, a second server storing attribute information and structure information of a file and attribute information of the directory, and a third server storing content data of the file; and executing, through the multiple servers, the data processing operations respectively corresponding to the multiple servers to rename the file system object.

Abstract: The present disclosure provides a metadata tree snapshot method and apparatus, a metadata tree query method and apparatus, and an electronic device, and relates to the field of data processing technology, and in particular to the field of cloud computing and cloud database technology. The specific realization scheme is as follows: acquiring a basic metadata tree and a first incremental metadata tree, where the basic metadata tree is created based on first snapshot data, the basic metadata tree is locked after being created, the first snapshot data is created at a previous snapshot time instant, and the first incremental metadata tree is created based on a metadata change operation after the basic metadata tree is created; locking the first incremental metadata tree in response to reaching a current snapshot time instant; and creating second snapshot data based on the basic metadata tree and the locked first incremental metadata tree.

Abstract: Protection of a kernel from a sniff and code reuse attack. A kernel mode page table in initialized in a kernel. The kernel page entries in the kernel mode page table are set from s-pages to u-pages. Supervisor mode access prevention is enabled in the u-pages. Code contained in the kernel page entries in the u-pages is executed, the kernel page entries in the u-pages are capable of execution but are not capable of being accessed and read directly.

Abstract: A hydrodynamic water blocking device for an underground garage includes a water blocking plate assembly and side rail assemblies, wherein the water blocking plate assembly includes a first water blocking element, one end of the first water blocking element is rotationally connected with a base, the other end of the first water blocking element is rotationally connected with one end of a second water blocking element, the first and second water blocking elements have foamed layers, the base has grooves capable of accommodating the embedded foamed layers, water inlets formed in the base communicate with the grooves, each of the side rail assemblies includes a side plate with an ascending rail including a horizontally disposed linear rail and an arc-shaped lifting rail, the second water blocking element has a walking assembly embedded in the ascending rail which is connected with a driving mechanism installed at the second water blocking element.

Abstract: A trace detection device including: an ion mobility tube ; a sampling gas path module ; a sample injection gas path module configured to introduce a sample carrier gas containing a sample collected by the sampling gas path module toward the ion mobility tube; and a gas chromatography apparatus capable of pre-separating the sample carrier gas, so as to form a pre-separated sample carrier gas; wherein the sample injection gas path module is further configured to be capable of switching between a first mode and a second mode, in the first mode, the sample injection gas path module introduces the sample carrier gas into the ion mobility tube; and in the second mode, the sample injection gas path module introduces the sample carrier gas into the gas chromatography apparatus to pre-separate the sample carrier gas, and the pre-separated sample carrier gas is introduced into the ion mobility tube.

Abstract: Provided are an odor sniffing device (11) and a vehicle-mounted security inspection apparatus for a container (1). The odor sniffing device (11) includes a primary sampling front end (116), which has a vent adapter (116-1) having a shape matching with a vent of the ventilator of the container, so that when the primary sampling front end (116) fits with the ventilator, the vent adapter (116-1) and the vent generally cooperate to achieve fluid communication. The vehicle-mounted security inspection apparatus (1) may perform imaging inspection and chemical inspection simultaneously.

Abstract: Protection of a kernel from a sniff and code reuse attack. A kernel mode page table in initialized in a kernel. The kernel page entries in the kernel mode page table are set from s-pages to u-pages. Supervisor mode access prevention is enabled in the u-pages. Code contained in the kernel page entries in the u-pages is executed, the kernel page entries in the u-pages are capable of execution but are not capable of being accessed and read directly.

Abstract: A global secondary index method for a distributed database, includes: obtaining original data to be written in response to a database writing request; writing the original data into the distributed database; performing global secondary index processing on the original data written into the distributed database to obtain global secondary index data; establishing global secondary index tables between the global secondary index data and data table primary keys in the distributed database; and writing the global secondary index tables into an index shards based on an asynchronous processing manner.

Abstract: With the method for snapshotting metadata, in response to reaching a current snapshot moment, a second basic version number of a binary search tree in a database at the current snapshot moment is generated according to a first basic version number at a previous snapshot moment; during a process from the current snapshot moment to a next snapshot moment, whenever metadata in the database is updated, the binary search tree is updated according to the updated metadata, and an updated version number of the binary search tree after each update is generated according to the second basic version number; and in response to reaching the next snapshot moment, a snapshot operation is performed on binary search trees corresponding to all version numbers generated between the current snapshot moment and the next snapshot moment to generate snapshot information of the current snapshot moment.

Abstract: A method for reading data includes: receiving a data reading request; acquiring a data writing file in response to determining that the data reading request triggers a reading-writing conflict event, in which the data writing file includes a writing version number and transaction information; obtaining an adjusted writing version number by adjusting the writing version number based on the request version number in response to determining that the data reading request satisfies a version adjustment condition based on the request version number, the writing version number and the transaction information; and performing data reading based on the data reading address and the adjusted writing version number.

Abstract: Embodiments of the present disclosure provide a real-time calibration device, a real-time calibration method and a detection apparatus. The real-time calibration device is in fluid communication with a sample injection pipeline of the apparatus to be calibrated. The real-time calibration device is configured to release a trace amount of calibration agent molecules during a sample injection of the apparatus to be calibrated, so that the trace amount of calibration agent molecules and a sample entering the apparatus to be calibrated are mixed and together enter the apparatus to be calibrated, and information of the sample and the calibration agent is detected by the apparatus to be calibrated, thereby performing a calibration.

Abstract: A hydrodynamic water blocking device for an underground garage includes a water blocking plate assembly and side rail assemblies, wherein the water blocking plate assembly includes a first water blocking element, one end of the first water blocking element is rotationally connected with a base, the other end of the first water blocking element is rotationally connected with one end of a second water blocking element, the first and second water blocking elements have foamed layers, the base has grooves capable of accommodating the embedded foamed layers, water inlets formed in the base communicate with the grooves, each of the side rail assemblies includes a side plate with an ascending rail including a horizontally disposed linear rail and an arc-shaped lifting rail, the second water blocking element has a walking assembly embedded in the ascending rail which is connected with a driving mechanism installed at the second water blocking element.

Abstract: A sampling probe, an automatic sampling device, and a container detection system are provided. The sampling probe includes: a mounting base; a housing mounted on the mounting base, a first accommodation chamber having an opening being defined in the housing, and an exhaust hole in communication with the first accommodation chamber and outside of the housing being formed in the housing; a coupling portion formed on an outer edge of the opening of the first accommodation chamber and formed to be hermetically coupled with an air outlet of a container; and a suction device mounted on the housing and configured to suck gas in the container into the first accommodation chamber through the air outlet. The sampling probe may collect the odor of toxic and harmful gases/hazardous chemicals inside the container at the air outlet of the container, without destroying the overall structure of the container.

Abstract: A sampling tube bundle includes a tube bundle body and a joint assembly. The tube bundle body includes a gas sampling tube for transmitting sampling gas; a metal woven layer wrapping an outer circumference of the gas sampling tube; a heating pad comprising a heat tracing cable wrapping an outer circumference of the metal woven layer, for heating the sampling gas in the gas sampling tube; a flame resistant tape wound around an outer circumference of the of the heating pad; a plurality of signal transmission lines circumferentially spaced apart from one another are arranged outside the flame resistant tape; and a sheath located outside the signal transmission line. The joint assembly is arranged on an end of the tube bundle body, for connecting to an analysis device or a sampling device.

Abstract: There are provided an ion mobility spectrometer and a sniffer. The ion mobility spectrometer includes: an ion migration tube; a sampling gas path having a sampling device configured to temporarily store a sample gas collected by a sampling head in a sampling pipe; a sample introduction gas path having two ends in communication with the gas inlet and outlet of the ion migration tube respectively, and configured to introduce a carrier gas within the ion migration tube into the sampling pipe and to carry a sample gas temporarily stored in the sampling pipe into the ion migration tube; and a valve assembly configured to only allow gas to flow from the sampling device to the sampling pipe in a sampling state, and to only allow gas to flow from the ion migration tube through the sampling pipe back to the ion migration tube in a sample introduction state.

Abstract: The present disclosure provides a trace detection device. The trace detection device includes: a box body comprising a main body frame and a top plate, the top plate and the main body frame forming a fully enclosed cavity; an ion migration tube assembly in the cavity and on a first side of the cavity; and a preamplifier and high voltage circuit board in the cavity and on a second side of the cavity, the second side being opposite to the first side.

Abstract: The present disclosure discloses a gas chromatograph-ion mobility spectrometry combined equipment, including: a gas chromatograph device for pre-separating a to-be-detected sample to form a pre-separated sample; an ion mobility spectrometry device in fluid communication with an outlet of the gas chromatograph device for detecting the pre-separated sample; and a gas circulating device in fluid communication with a discharged gas interface of the ion mobility spectrometry device for processing a discharged gas from the ion mobility spectrometry device, wherein the gas circulating device is further in gas communication with the gas chromatograph device for conveying a part of the discharged gas to the gas chromatograph device to serve as a carrier gas, which drives the to-be-detected sample to enter the gas chromatograph device. The miniaturization and the portability of the gas chromatograph-ion mobility spectrometry combined equipment are improved.

Abstract: Techniques for virtual machines include receiving virtual machine (VM) requests, and finding one or more VM requests of the VM requests that optimize available resources of a candidate host machine while seeking to minimize differences between the one or more VM requests and the candidate host machine. The one or more VM requests are allocated to the candidate host machine.

Abstract: The present disclosure provides a gate system for sample detection and a method of sample inspection, which relate to the field of detection and analysis technology. The gate system comprises: an accommodating apparatus configured to accommodate an inserted ticket to be detected; a wipe sampling apparatus including a wipe sampling belt which is configured to drive the ticket to be detected to move within the accommodating apparatus and to conduct a wipe sampling to the ticket; an inspiratory sampling apparatus configured to collect samples dropped from the wipe sampling apparatus; and a detection apparatus configured to detect the samples and output detection results. The gate system for sample detection and the method of sample inspection provided by the present disclosure have a wide range of applications and can perform rapid sampling and detection to those substances that are difficult to be volatilized.